1870.] 105 [Cope. 
in Sibbaldius tectirostris, Cope. The whole form is very different from 
that of the MZ. lonyimana. he depth and length of the bone on the 
interior (median) face, are about equal. The otic bulla is subcylindric, 
a little flattened on the inner side ; its surface is quite smooth. 
The ramus of the mandible is slender, and when viewed from above, 
considerably curved. It has an elevated subtriangular and acuminate 
coronoid process, quite as in a Balenoptera. (Fig. 24 from above.) Prox- 
imally the ramus has a slight sigmoid curve viewed from the side (fig. 23), 
and in the general is more slender than that of M. longémana, in profile. 
The angular process is prominent ; the shaft is plane on the inner side, on 
the external very convex; it is nowhere compressed, and the external 
pores are widely separated. 
Fig. 25. 
The atlas has no neural spine and no tubereulum atlantis, The dia- 
pophyses are compressed, irregularly truncate, their inferior margin con- 
siderably above the fundus of the foramen dentati. The axis presents a 
rudimental odontoid process. Its diapophysis and parapophysis are pot 
very stout, and the former is the longer. The parapophyses diminish 
rapidly till the fifth vertebra presents only a rudiment on one side. The 
articular faces of these cervicals are a transverse ovate. The diapophyses 
are slender and straight. (See figs. 26 atlas, 27 axis, and 28, third cer- 
vical. ) 
Fig. 27 Fig. 28. 
Two of the diaphophyses of the caudal vertebr are hocked in form, 
owing to the failure to isolate anteriorly the foramen which pierces them. 
The scapula is without rudiment of coracoid and is longer than deep ; its 
proportions are similar to those of M. osphyia. 
The fore limbs are neither of them quite complete. The epiphysis of 
the humerus is still free, and indicates that the animal was young when 
captured. The bones of the forearm are much as figured by Rudolphi 
A. P. §.—VOL. XII—N 
