12 H. B. POLLARD. 



Only the end of the snout reconstructed. The specimen was young 

 but replacement of cartilage by bone has proceeded to a considerable 

 extent, especially in the rostral region. 



The median cartilage of the rostral region slopes sharply downwai'ds 

 and forwards, and, viewed from the side, its profile is curved. The floor 

 of the nasal cavity extends laterally as two wings, actually prolonged 

 still more laterally by the prefontal bone. At the median anterior part 

 of the rostral region there are abundant traces of resorption of cartilage, 

 showing that a more distinct rostral prolongation was present at an 

 earlier stage. This resorption is the cause of the irregular appearance 

 of the anterior face as seen in the model. 



Below the junction of the lateral and medial portions, a remarkable 

 though slight projection of cartilage (* Fig. 7) bears the prepalatine 

 bones, of which the large cartilaginous apophyses are seen in the figure, 

 placed curiously close together and, along with the so called ethmoid 

 bone, reaching very near to the tip of the snout. 



Below and in front of the prepalatine cartilage is seen the three- 

 rayed, procartilaginous premaxillary piece, forming the tip of the 

 snout (Pmx. p.). 



The maxillary tentacle (Mx. t.) is attached to the prepalatine car- 

 tilage through the intermediation of the maxillary bone. The tentacle 

 itself passes sharply dow T nwards and backwards, below the coronoid 

 tentacle. Behind the maxilla lie the paired, external tentacle-like 

 supports of the velum (/. v. s.). 



Only the mentomeckelian portion of the lower jaw (m. Mck.) is seen 

 in the model. A coronoid process is not developed, and the coronoid 

 piece is only represented by a procartilaginous rudiment, not shown in 

 the model. The coronoid tentacle (Oor.t.) proceeds backwards, almost 

 parallel with the mentomeckelian cartilage, and it is fused with the 

 distal portion of the mental tentacle {Merit, t.). The mental tentacles, 

 which have a beautifully curved form, are fused with one another at 

 their bases in the middle line, below the premaxillaiy piece. The 

 junction is in front of, and slightly below the symphysis of the dentary 

 bones. 



The distal fusion of the mental and coronoid tentacles deserves 

 especial attention. 



