DELPHINAPTERUS. 103 



form outer part of beak. Vertex cranii somewhat 

 higher than nasals. Pterygoids separated by a wide 



cleft. Teeth oblique and truncated, "5" ~q~ = 38. Man- 



dible 15| inches long, symphysis 2^ inches long. 

 Tympano-periotics absent. Monro Collection. 



2. Skull, adult, 23 inches long, breadth 13 inches; beak, 



length 14 inches, breadth 7| inches. Premaxilla3 faintly 



concave at nasal end ; breadth opposite base of beak 



2^ inches, then convex almost to tip, which has a 



blunt, rounded end. Superior maxillae distinct. 



Vertex and upper ends of nasals in same plane. 



Pterygoids as in No. 1. Teeth oblique, truncated, 



9 10 



- — = 36. Mandible 19 J inches, symphysis 3| inches 



long. Tympano-periotics absent. Spitzbergen. 

 Lamont Expedition. Donor — Dr A. M. Bentley. 



3. Pectoral Limb, left. Humerus 6 inches long ; radius 4f 



inches long, 2| inches broad ; ulna 4^ inches long, 



2^ inches broad; epiphyses fused. Carpus with 



radiale, intermedium, and a cartilaginous ulnare ; the 



distal carpalia are C^ for pollex, Co mainly for M^, 



Cg very small for Mij; , and C4 equally for Mjij and 



Mjy ; no independent Cg. Phalangeal formula : pollex, 



Phj or 2 ; digit ii., Ph^ ; digit iii., Phj; ; digit iv., Ph^ ; 



dioit v., Ph.. Struthers Collection. 



[Tympano-periotic, from specimen in Museum, Royal 



College of Surgeons, England. Tympanic length 



ly^Q inch, breadth 1 inch, height f^ inch. Outer 



surface saddle-shaped, lip-like process extending 



vertically down it ; inferior surface bilobed, outer 



larger, smooth, rounded ; inner ridged, rough ; cleft 



deep, extending forward towards anterior end, above 



which is Eustachian opening. (Figure of inferior 



surface below.) Periotic l^- inch long, 1 inch broad; 



dense labyrinthine part almond-shaped.] 



