Maurolicus pennanti (Walb.). 1792. Walbaumin, Artedi. Pisc., p. 47. 1835. Nilsson, Observ. Zool., p. 9 (borealis). 1838. Cocco, Lett. su Salmoni, p. 32, pl. iv, fig. 12 (amethystino punctatus). 1871. Klunzinger, Verhl. K. K. Zool. Bot. Ver. Wien., vol. xxi, p. 593 (mucronatus). 1875. Hutton, Tr. N.Z. Instit., vol. vii (1874), p. 250 (australis). 1913. Gilchrist, Mar. Biol. Rep., vol. i, p. 66 (name only: amethystino punctatus). Depth of body 4-41, length of head 31, in length of body. Eye 11 times larger than snout, twice interorbital width, 21-23 in length of head. D 10, A 10+15. Photophores: a suborbital, 3 on operculum, a pair on chin at symphysis, 6 at bases of anterior branchiostegals, 6 from isthmus to pectoral, a lower row of 12 from (just in front of) pectoral to ventral, an upper row of 8-9 from behind pectoral to ventral, 5-6 from ventral to vent, 16 along base of anal, 7 from anal to caudal. Length.-Up to 65 mm. Colour.-Brilliant silvery, back dark greenish brown. Distribution.-Tristan d'Acunha (South African Museum), N. and S. Atlantic, Mediterranean, Japan, New Zealand, Red Sea. Frequently found floating dead on surface, or cast up on beach after storms. Gen. ARGYROPELECUS Cocco. 1829. Cocco, Giorn. Sci. Sicil., fasc. 77, p. 146. 1906. Brauer, Wiss. Erg. D. Tiefsee Exp., vol. xv, pt. 1, p. 101 (references and account of genus). 1908. Regan, Tr. Linn. Soc. Zool., vol. xii, pt. 3, p. 218 (key to species). Body short, strongly compressed, hinder part abruptly narrower. Skin naked, with photophores on head and lower side of body and tail. Mouth very oblique, large. Teeth minute, on both jaws and palatine, those on premaxilla and maxilla in a single series. Pectorals well developed. Ventrals very small. Bones of the shoulder and hip girdles prolonged into pointed processes projecting outside the body. A series of sharply keeled scutes from below pectorals along belly to ventrals. Dorsal short, preceded by several neural spines forming a triangular bony plate. Anal short, rays divided into 2 groups or the fin completely divided into 2 portions. Adipose dorsal rudimentary. Caudal forked. Lateral line absent. Gill-rakers very long. Pseudobranchiae present. Branchiostegals 9. Air-bladder present. Pyloric caeca few (4). Eyes directed upwards, very close together, the interorbital space very narrow, the supraoccipital ridges almost contiguous. A small genus of widely distributed species. They are bathypelagic, but in all probability frequently ascend to or near the surface at night. The elongation of the eyes in a vertical direction, so that they gaze upwards instead of sidewards or forwards, forms a noticeable character separating them from the allied genera Sternoptyx and Polyipnus. The photophores are remarkably constant in position and number. There are always (in the adult) 50, arranged as follows: 1 preorbital, 1 postorbital on the operculum, 2 near lower margin of operculum, 6 on the branchiostegal membranes, 6 along isthmus, followed by 12 along ventral keel, 2 above base of pectoral, and 20 from pectoral to caudal; the latter row is divided (except in affinis) into groups of 6 from pectoral to ventral, 4 pre-anal, 6 supra-anal, and 4 caudal. Young stages are described in Brauer's work. There is considerable variation in the proportions of the body according to age. 1899. Garman, Mem. Mus. Comp. Zool., vol. xxiv, p. 237. 1906. Brauer, Wiss. Erg. D. Tiefsee Exp., vol. xv, pt. 1, p. 103, pl. vii, figs. 1, 2, text-figs. 43, 44. Depth of body 23, length of head 3, in length of body. Hinder part of body not very abruptly narrower, its greatest depth 13 in greatest depth of fore part of body. Eye larger than snout, 212 in length of head. Dorsal and ventral ridges not serrated, no spines on lower surface of tail. angle of preoperculum, 1 at end keel. D VII +9, A 13 (7+6). caudal in a continuous series. One spine on post-temporal, 1 at of isthmus, and 2 at end of ventral Photophores from the ventrals to the (Plate VIII, fig. 1.) Length.-Up to 45.5 mm. Colour.-Silvery, blackish along back, eyes with metallic sheen. Locality.-Off south-west coast of Africa (31° S., 8° E.), 1000 fathoms. Distribution.-West Indies, Gulf of Guinea, Indian Ocean, 5001250 fathoms. This species is almost certain, sooner or later, to be captured within our limits, and is therefore included for the sake of comparison. Argyropelecus olfersi (Cuv.). 1829. Cuvier, Règne Anim., 2nd ed., p. 316, pl. xiii, fig. 2. 1896. Collett, Res. Camp. Sci. Monaco, fasc. 10, p. 127, pl. iii, fig. 14. 1906. Brauer, Wiss. Erg. D. Tiefsee Exp., vol. xv, pt. 1, p. 108, text-fig. 46. 1916. Thompson, Mar. Biol. Rep., vol. iii, p. 72 (references). Depth of body 13-13, length of head about 3, in length of body. Hinder part of body very abruptly narrower, its greatest depth about twice in greatest depth of fore part of body. Eye greater than snout, 21-3 in length of head. Dorsal and ventral ridges not serrated, no spines on lower surface of tail. One spine on post-temporal, I at angle of preoperculum, 1 at end of isthmus, and 2 at end of ventral keel. D VII +9, A 12 (7+5). Photophores from ventrals to caudal in three groups, pre-anal (4), supra-anal (6), and caudal (4). Length.-Up to 99 mm. Colour.-Silvery, back blackish, eyes with metallic sheen. Distribution.-North and South Atlantic, Indo-Pacific. Argyropelecus hemigymnus, Cocco. 1829. Cocco, in Giorn. Sci. Sicil., fasc. 77, p. 146. 1906. Brauer, Wiss. Erg. D. Tiefsee Exp., vol. xv, pt. 1, p. 106, text-fig. 45. 1913. Gilchrist, Mar. Biol. Rep., vol. i, p. 66 (name only). Depth of body 13-2, length of head about 3, in length of body. Hinder part of body very abruptly narrower, its greatest depth 21 in greatest depth of fore part of body. Eye rather greater than snout, about 3 in length of head. Dorsal and ventral ridges not serrated, no spines on lower surface of tail. One spine on post-temporal, 2 at angle of preoperculum, 1 at end of isthmus, and 1 at end of ventral keel, the last mentioned one projecting backwards and finely and variably denticulate both on its upper and lower edges. D VII +7-8, A 11 (6+5). Photophores from ventrals to caudal in three groups as in olfersi. Length.-Up to 40 mm. Colour. Silvery, back blackish, eyes with metallic sheen. Distribution.-North and South Atlantic, Mediterranean, Indian Ocean. This species seems to be commoner in these waters than olfersi, judging from the relative numbers of specimens taken by the s.s. Pieter Faure." 66 Gen. STERNOPTYX Herm. 1781. Hermann, Der Naturforscher., vol. xvi, p. 8. 1887. Günther, Challenger Rep., vol. xxii, p. 168. Body short, strongly compressed, hinder part abruptly narrower. Skin naked, with photophores on head and lower side of body and tail. Mouth very oblique, large. Teeth minute, in several series on both jaws, the largest in the inner row; none on vomer or palatine. Pectorals well developed. Ventrals very small. Bones of the shoulder and hip girdles prolonged into pointed processes projecting outside the body. A series of sharply keeled scutes along belly to ventrals. A transparent membrane, on which anal fin is situated, between ventrals and base of caudal peduncle. Dorsal short, preceded by a triangular bony plate. Anal rather long, undivided. Adipose dorsal more or less developed. Caudal forked. Lateral line absent. Gill-rakers long on upper, but rudimentary on lower, part of arch. Pseudobranchiae present. Branchiostegals 5. Air-bladder present. Eyes lateral, the supraorbital and occipital ridges well separated. Only a single species known. Sternoptyx diaphana Herm. 1781. Hermann, loc. cit., p. 8, pl. i, figs. 1, 2. 1887. Günther, loc. cit., p. 169, pl. xlv, figs. D, D1. 1906. Brauer, Wiss. Erg. D. Tiefsee Exp., vol. xv, pt. 1, p. 115, text-figs. 56-63. 1911. Zugmayer, Res. Camp. Sci. Monaco, fasc. 35, p. 54, pl. ii, fig. 5. 1924. Gilchrist and von Bonde, Fish. Mar. Surv. Spec. Rep., vii, p. 9. Proportions of body variable. Depth of body nearly or quite equal to length, length of head about 23. Eye variable, about 2 in length of head, much larger than snout. DI+9-12, A 12-14. Photophores : 1 postorbital, 2 near lower margin of operculum, a group on branchiostegal membrane, 5 on isthmus, followed by 10 along ventral keel, 3 above pectoral, 3 pre-anal, 3+1 supra-anal, and 4 caudal. Length.-Up to 50 mm. Colour.-Silvery, back blackish. Locality.-Off Cape Point, 312-1014 fathoms. Distribution.-Atlantic and Indo-Pacific (but not in high latitudes), surface to 2500 fathoms. Probably rises to the surface at night. Gen. POLYIPNUS Gnthr. 1887. Günther, Challenger Rep., vol. xxii, p. 170. 1899. Alcock, Ind. Deep-Sea Fish., p. 137. Body short, strongly compressed, hinder part not abruptly narrower. Skin with large, extremely thin and deciduous scales; photophores strongly developed. Mouth vertical, large. Teeth minute in several series in both jaws, and on vomer, none on palatine. Eye lateral, supraorbital and occipital ridges well separated. Pectorals and ventrals well developed. Bones of pectoral and pelvic girdles projecting, but not prominently; a striated and denticulated fan-shaped bony process below base of pectoral. A series of sharply keeled scutes along belly. A strong spine on each post-temporal, being a continuation of the occipital ridge. Dorsal moderate, preceded by a small bifurcate spine. Anal moderate, undivided. Adipose dorsal present. Caudal forked. Lateral line absent. Gill-rakers long. Branchiostegals 9-10. Pseudobranchiae present. Air-bladder present. This genus is confined to the warmer parts of the Atlantic and Indo-Pacific, and Southern Australia. Several species have been described, but it is probable that most of them are varieties of spinosus. Polyipnus spinosus Gnthr. 1887. Günther, loc. cit., p. 170, pl. li, fig. B. 1904. Jordan and Starks, Bull. U.S. Fish. Comm. for 1902, p. 581, pl. ii, fig. 3 (stercope). 1905. Gilbert, ibid. for 1903, p. 609, pl. lxxiii (nuttingi). 1906. Brauer, Wiss. Erg. D. Tiefsee Exp., vol. xv, pt. 1, p. 120, pl. vii, fig. 3, text-figs. 64-66. 1914. McCulloch, Endeavour Res., vol. ii, pt. 3, p. 87, pl. xvi, textfig. 4 (tridentifer). |