Fam. 2. TRACHYPTERIDAE. Deal-fishes and Oar-fishes. Skeleton feebly ossified. Postslender, or absent. Dorsal fin anterior rays prolonged. Anal Ventral fins with never more Body elongate, ribbon-shaped. Scales absent. Mouth very protractile with a few feeble teeth. temporal simple. Ribs small and extending from head to end of tail, absent. Caudal present or absent. than 7-9 rays, often reduced or obsolete. Lower pharyngeals toothless. Vent about in middle of body. Pseudobranchiae present. Air-bladder absent. Two genera, both of which occur in South Africa. Ventral fins well developed, consisting of 6-9 rays. Caudal fin present, divided into a larger portion projecting upwards and a smaller lower portion. Lateral line spiny. Although comparatively little is known about the habits of these fishes, they appear to inhabit deep water and only after storms are seen in shallow water or cast on the beach. Owing to the fragility of both the skeleton and flesh, nearly all specimens are more or less damaged. Many species have been described from such mutilated specimens, but it is probable that only a few species should be recognised, the majority being synonymous. The younger stages have been studied in the Mediterranean, and a resumé with figures will be found in Smitt's work (loc. cit.). The most remarkable feature of the young fish is the great elongation of the anterior rays of the dorsal and the rays of the ventral and caudal fins. The caudal fin in the early stages is symmetrical and only becomes bipartite later, when the elongate rays of the lower portion are broken off and the upper portion becomes turned upwards like a fan. Key to the South African species. 1. Greatest depth of body near the occiput 2. Greatest depth in the middle of body iris. arcticus. |