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Show 480 DR. W. G. RIDEWOOD ON THE CRANIAL [Dec. 13, consists merely of a semi-tubular scale touching the back of the supratemporal. The supratemporal is a tubular scale which does not exhibit the usual triradiate character, since the parietal division of the sensory canal branches in the skin just anterior to the supratemporal 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. Circumorbital 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. ■Maxillary 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 difficult to understand what purpose 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 Engraulis, attaining a maximum in Engraulis mystax and Engraulis setirostris (Cuvier and Valenciennes, Hist. Nat. Poiss. xxi. 1848). The actual length of the projecting part of the maxilla varies in different specimens of Coilia, doubtless owing to fracture during life; but it may be taken as a rule that the toothed part of the maxilla is two-and-a-lialf times as long as the tooth-bearing part of the dentary. The premaxi 11 te extend below the mesethmoid, not in front of i t ; they nearly touch, but do not actually meet in a symphysis. There are two surmaxilla?. Mandibular Series (text-figs. 137 and 138, pp. 479, 481).-The mouth is so large that the ramus of the mandible is longer than the cranium. The dentary and articular components of the coro-noid process a,re separated by a short interval. This separation, however, although striking, is evidently a feature of no great importance; it occurs in an exaggerated form in Gonorhynchus, it occurs in some Percoid and Berycoid fishes, and doubtless in many other groups. The dentary bears teeth similar to those on the maxilla and premaxilla. The angular is not distinct from the articular, and there is no sesamoid articular. Hyopalatine Series (text-fig. 138, p. 481).-In relation with the great size of the mouth the quadrate articulation is thrown far back, and both quadrate and hyomandibular bones are backwardly rotated. The head by which the hyomandibular articulates 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 straight, and the palatine articulates with the prefrontal by two contiguous heads, which are right and left, not anterior and posterior. Teeth are borne on the edge of the palatine and the anterior part of the edge of the ectopterygoid. Opercular Series (text-fig. 137, p. 479).- The opercular bone has a |