480 DR. W. G. RIDEWOOD ON THE CRANIAL [DeC. 13, 



consists mei-ely of a semi-tubular scale touching the back of the 

 supratempoi'al. The supratemporal is a tubular scale which does 

 not exhibit the iisual tiiracliate character, since the parietal 

 division of the sensoiy canal branches in the skin just anterior to 

 the supi-atemporal bone. The axis of the preopercular slopes 

 strongly backward ; the anterior edge of the bone is concave and 

 not angulate, so that the proportions of the upper and lower 

 limbs cannot be determined. 



Circumorhital Series (text-fig. 137, p. 479). — The nasal is very 

 small. Beneath the nasal sac are two bones, both rather firmly 

 attached to the prefrontal. There are three postorbitals and three 

 suborbitals, the former series making an acute angle with the 

 latter. 



Maxillm^y Series (text-fig. 137, p. 479). — The extraordinary 

 length of the maxilla is one of the most remarkable features of the 

 fish under consideration ; indeed, it is difiicult to understand what 

 piirpose the teeth on the hinder part of the maxilla can possibly 

 serve. A similar prolongation of the maxilla is met with in some 

 species of Engrcmlis, attaining a maximum in Engratdis mystax 

 and Engrmdis setirostris (Cuvier and Valenciennes, Hist. Nat. 

 Poiss. xxi. 1848). The actual length of the projecting part of 

 the maxilla varies in difiei'ent specimens of Coilia, doubtless 

 owing to fracture cUuing life ; but it may be taken as a rule that 

 the toothed part of the maxilla is two-and-a-half times as long as 

 the tooth- beaiing part of the dentary. The pi-emaxillse extend 

 below the mesethmoid, not in front of it ; they nearly touch, but 

 do not actually meet in a symphysis. Thei-e are two sui-maxillas. 

 Mandibular Series (text-figs. 137 and 138, pp. 479, 481).— The 

 mouth is so large that the i-amus of the mandible is longer than 

 the cranium. The dentary and ai-ticular components of the coro- 

 noid process are separated by a short interval. This separation, 

 however, although striking, is evidently a feature of no great 

 importance ; it occui-s in an exaggerated form in Gonorhynchus, 

 it occurs in some Percoid and Beiycoid fishes, and doubtless in 

 many other groups. The dentaiy bears teeth similar to those on 

 the maxilla and pi'emaxilla. The angulai- is not distinct from the 

 articular, and there is no sesamoid articular. 



Hyopalatine Series (text-fig. 138, p. 481). — In relation with the 

 o-reat size of the mouth the quadrate aiticulation is thrown far 

 back, and both quadrate and hyomaiidibulai' bones ai-e backwardly 

 rotated. The head by which the hyomandibulai' ai'ticulates with 

 the cranium is small and single (see p. 478). The symplectic is 

 not in a direct line with the axis of the hyomandibular, but forms 

 an angle of about 140 degrees with it. The metapterygoid is 

 large,"and the entopterygoid small. The ectopterygoid is nearly 

 stiaight, and the palatine articulates with the prefrontal by two 

 contiguous heads, which are right and left, not anterior and 

 posterior. Teeth are boi'ne on the edge of the palatine and the 

 anterior part of the edge of the ectopterygoid. 



Operctdar Series (text-fig. 137, p. 479). — The opercular bone has a 



