5 



231 



fishes. The centra are grooved-striate, and without large longitudinal fossae 

 anterior to the thirteenth. 



The premaxillary bone is somewhat curved in a longitudinal direction. 

 At its anterior extremity, there is a short series of large teeth, which continues 

 gradually or abruptly into a series of much smaller teeth along the inner or 

 posterior border of the alveolar face. This terminates in one or two abruptly 

 larger teeth near the distal end of the bone. The outer alveolar border is 

 occupied by a row of teeth of large size, similar to those at the proximal 

 end, which commences opposite the most distal of the latter. Their size is 

 reduced opposite to the two large distal ones, and is recovered again in the 

 single row on the narrow distal portion of the maxillary. The teeth are 

 compressed at the tip, and generally bear one or more cutting-edges. 



The dentary bone would support about twenty large teeth, directed 

 oblicptely inward and upward, were they placed at regular distances ; but 

 they are in all specimens unequally spaced, owing to frecpient shedding and 

 replacement. The bases of the teeth are round, and the crowns become 

 compressed to the tip. They are strongly curved backward, and acute. 

 The anterior margin is particularly convex and acute, forming a cutting-edge ; 

 but there is no edge on the posterior face. The surface is rather finely striate- 

 grooved on the inner and posterior faces. The teeth of the exterior series 

 are in several rows ; that next the large teeth being considerably larger than 

 the others. They are curved inward, and are flattened, having cutting-edges 

 on both anterior and posterior margins. Cementum smooth. The external 

 smaller teeth are shorter in relation to their length, not curved, and two- 

 edged. 



The dentary bone is narrow wedge-shaped, contracting regularly to the 



symphysis, and is thickened just within the inferior margin. The symphyseal 



surface is small, and presents a marked fossa. The external face of the bone 



is divided by a deep longitudinal groove, which is overhung by the produced 



extremity, and which gives exit to the mental foramen. The external face 



of the dentary has an impressed groove along its lower third anteriorly, 



and its surface is sculptured with deep longitudinal sulci, which often run 



together. 



Measurements. m. 



Length of a fragment 0. 28 



Depth at the first tooth 0.01 



Depth at the seventh tooth 0.028 



Depth at the eleventh tooth 0. 0-10 



Total elevation of the fifth tooth 0.041 



a 



