1904,] OSTEOLOGY OP THE ELOPIDiE AND ALBULID^, 67 



bone and carries the sensory canal from the antero- ventral corner 

 of the supratemporal downwards to the upper end of the pre- 

 opercular. This bone I propose to term the subtemporal. The 

 real supratemporal of the Salmon was overlooked by Parker alto- 

 gether, although it is a larger bone than the subtemporal. It 

 lies between the post-temporal and the back of the squamosal, 

 and beai's the usual triradiate sensory canal. In Bruch's ' Yer- 

 gleichende Osteologie des Rheinlachses ' (Mainz, 1861), a work to 

 which, curiously enough, Parker refers (l. c. p. 142), both supra- 

 temporal and subtemjDoral are correctly shown, the former being 

 marked x" (pi. 2. fig. 1) and the latter x. 



The subtemporal attains its greatest development, so far as I am 

 aware, in the Oharacinid genus Sarcodaces, in which it appears 

 as a kind of supraopercular bone. Smith Woodward (Proc. Zool, 

 Soc. 1887, p. 536) has recorded the occurrence of a similar bone 

 in Rhacolepis, a Cretaceous Teleostean from Brazil which he is 

 disposed to associate with the Elopidpe. 



In Arapainut and Osteoglossttm the supratemporal is a stout, 

 partially sculptm^ed bone, firmly united with the cranium 

 (squamosal and parietal bones). In the Mormyridae it is a large, 

 thin scale of bone forming a loose lateral cover to the lateral 

 cranial foramen, and in JVotopterios the relations are the same, 

 although the supratemporal bone itself is much smaller. In 

 Hyodon the supratemporal is a large curved scale of triangular 

 shape, which unites in the dorsal median line with its fellow of 

 the opposite side, and covei's the whole of the parietal and a small 

 part of the frontal as well. In his " SjTiopsis of the Families of 

 Teleostean Fishes" (Ann. & Mag. Nat. Hist. (7) xiii. 1904, p. 164) 

 Boulenger groups the Mormyridfe with the Hyodontidte on the 

 ground that they both have the " supratemporal large, plate-like, 

 covering the greater part of the parietal bone." As a matter of 

 fact the supratemporal of the Mormyridse covers very little of 

 the pai'ietal. In Petrocephalus heme it just overlaps the lateral 

 edge of the parietal, in Mwmyrus oxyrhynchus it just touches 

 the postero-lateral corner, while in Mormyrops deliciosits and 

 Gymnarchus niloticics it does not reach the parietal at all. 



In Ulojjs and Megalops the supratemporal is a scale extending 

 inwards as far as the median plane of the head, overlapping the 

 top of the opercular bone, and attached by its anterior edge to 

 the transverse parieto-squamosal ridge. The transverse com- 

 missure of the sensory-canal system thus does not run in the 

 parietal, but above it. Each supratemporal is notched behind, 

 giving the impression of a transverse row of four bones. In 

 Dussicmieria the notch completely divides the bone, giving a series 

 of four, the laterals of which, according to the foregoing definition, 

 alone can claim to be regaixled as supratemporals. In Chanos 

 there is a series of eight such bones. Those nearest the median 

 plane are narrow tubular bones, the next are fused early with the 

 parietals (the former fuse later with the latter), then come the 

 supratemporals, and outermost of all the subtemporal. 



5* 



