224 PROCEEDINGS OF THE ACADEMY OF 



vertebrae longer than their greatest diameter. Dorsal fin wanting. Gularand 

 pectoral region without folds. Scapula with well developed acromion and 

 coracoid. Baleen narrow, short. 



Agaphelus gibbosus Cope. 



Scrag Whale, Dudley, Philos. Trans, xxxiii., 250, and of The Whalers. 

 jBalana ffibbosa ^Tx\ehen, Systema Mammalium 610 (from Dudley), and after 

 him of Gmelin, Bonnatere, Lacep^de, Virey, Gerard, Desmarest & Fischer. 

 Gray, Catal. Brit. Mus. 1850, p. 18, and 18t5G, p. 90. 

 Agaphelus yihbosus Cope, Proc. Ac. N. Sci. Phila., 1868, 159. 

 Balxnoptera rostrata Cope, Proc. Ac. Nat. Sci., Phila., 1867, 147. 



Ft. In. 



Total length (estimated) of young 43 



Length to third caudal vertebra 33 



Length of cranium (estimated) 6 10 



" mandibular ramus (in curve) 6 



" pectoral limb 4 



Width of " " 15 



Length of humerus 11-5 



" radius and ulna 17 



Posterior margin of scapula 14 



Length of coracoid from glenoid cavity 3-3 



" glenoid cavity , 6-3 



Mandible, length from condyle to coronoid 13-5 



" depth at coronoid 85 



" " 2-5 feet from coronoid ^ 4-6 



The form of the mandibular ramus is peculiar, and more like that of the 

 Bala?noptera rostrata than anj^ other. It is triangular in section, having 

 an inferior angulated ridge, and a broad, slightly convex, superior face, instead 

 of their usual ridge. Such a ridge leaves the coronoid process, but soon turns 

 inwards to form the inner outline. Width of the superior face 3-5 inches. 

 The coronoid process is quite elevated, and turned outwards. In the fresh 

 animal the lower lip included the upper all round. The laminae of whalebone 

 are jilaced on a base having a sigmoid flexure. Greatest depth of the gum 1 

 in. 3 lines. Within each principal lamina are two supplementary laminie, the 

 intermediate being the narrower, the inner triangular, its intermediate bristles 

 arising from the gum. The bristles of the supplementary plates are longer 

 and finer than those of the outer; in the latter, three series of bristles are en- 

 closed between very thin enamel plates. All the laminae are thin, five in an inch, 

 and split transversely straight; white cream- colored, with a purplish shade near the 

 centre of the base. The ulna is slender, but furnished with a prominent round- 

 ed and flattened olecranon, which is prolonged into a thin cartilaginous plate, 

 formed like the diapophysis of a vertebra, and in the plane of the ulna ; this 

 structure appears to have been ossified in the SibbaMius borealis Fisch., 

 as figured by Dubar In the Agaphelus gib b os u "it occasions an abrupt 

 angulation near the basal third of the inner margin of the fin. In the scapula, 

 the coracoid is in its plane, but the larger acromion diverges outwards. 



The anterior caudal vertebrt« are more elongate than the lumbosacral, less 

 depressed, and with the centra in every way larger. All are sharply keeled 

 on the median line below, with a concave face between the keel and the base 

 of the diapophysis. The caudal and lumbosacral diapophyses are obspatulate, 

 the anterior becoming narrower. The neural spines of the lumbar vertebrae 

 are much elevated, concave above both before and behind, the zygapophysis 

 measuring a point considerably below the middle. 



In. 



Third (?) caudal (not perforate) length centrum 7-3 



depth 6 



width 6-5 



[Sept. 



