190 DE. W. a. RIDEWOOD ON THE CRANIAL OSTEOLOGY OP 



flooring which lies immediately above the paraaplienoid. There 

 is no basispbenoid, and there are no separate prefrontals. 



Teonporal and Preopercular* Series (Pi. 22. fig. 1). — There are 

 but two limbs to the post-temporal. The epiotie limb is the 

 loDger of the two ; it is curved and slender. The other limb is 

 broad and sliort. aud extends forward towards the postero-ventral 

 angle of the supratemporal. There is no deep or opisthotic 

 limb. The supratemporal is a broad thin scale of bone, convex 

 externally, which covers the sup ero -lateral parts of the squamosal 

 and epiotie, and affords a lateral protection to the fibrous vesicle 

 which lies in the lateral cranial foramen. 



The interopercular is a comparatively thick bone behind, but 

 it thins off in front into a long, thin ossified ligament, which lies 

 in the groove that faces downward from the ventral edge of the 

 preopercular and quadrate. The vertical and horizontal limbs of 

 the preopercular are not clearly distinguishable, since the bone 

 has a uniform curve, with the concavity directed forwards and 

 upwards. A fair amount of the inner surface of the preopercular 

 shows between the hyomandibular, interopercular, and opercular 

 (fig. 4). 



Gircumorbital Series (fig. 1). — The nasal is fairly large, and 

 has the form of along semi-tubular bone which runs horizontally 

 over the nasal sac, and takes a sharp curve downward at its 

 anterior end, and terminates against the upper surface of the 

 premaxilla. The other bones of the series are four in number 

 on each side ; they are rather narrow, and in proportion to the 

 size of the skull are feebly developed. 



Maxillary Series (fig. 1). — The gape is premaxillary, and the 

 two premaxillai are fused in the median plane, the suture 

 being obliterated. Each premaxilla bears about thirteen teeth, 

 slightly curved, and bluntly pointed. The maxillae have no 

 teeth, aud their anterior ends are separated by the mesethmoid. 

 The anterior portion of each is narrow, the postero-ventral 

 portion is expanded into a racquet-shaped plate. There is no 

 surmaxilla. 



Mandibular Series (figs. 1 and 4). — The two dentary bones 



* The reasons for including the preopercular and interopercular bones in 

 this series, and excluding them from the opercular and branchiostegal series, 

 are given in a paper on the skull of the Elopidae, &c., shortly to be published 

 by the Zoological Society. For reasons given in the same paper it is considered 

 expedient to regard the post-temporal as a constituent of the skull. 



