92 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



being stippled in the drawing; the large sinus occupied by the mesethmoid 

 cartilage ; and the ample size of the longitudinal vascular canals. In the more 

 posterior cross section (Fig. A), none of the sutures are distinctly marked, hence 

 the relations of mesethmoid, pterygoids, and maxillaries at the base of the figure 

 are best understood through comparison with the photograph of these parts given 

 in Plate 2. In the same plate will be noticed the extremely well preserved 

 periotic elements, which have fortunately been retained in place, notwithstanding 

 the loss of the tympanic bullae. The periotics are more elongate than the corres- 

 ponding elements in Inia, with more bulbous promontory, and more strongly 

 developed processes for attachment with the bullae. It is noteworthy that in both 

 elements the stapes still remains seated in its proper orifice. The opening seen 

 on the inner side of the periotics in Plate 2, and also of the natural size in 



Figure B. 



Transverse section of rostrum in the type of Lophocetus taken at line of fracture along 

 which the forward extremity is severed off. X \. 



Plate 4, Fig. 2, where a foramen normally occurs, leads directly into the cranial 

 cavity ; this is empty, and its walls may be viewed from behind through the foramen 

 magnum. 



The occipital border of the skull is indistinctly shown in both plates by 

 reason of the fact that the atlas, within which is included also a portion of the axis, 

 remains firmly cemented to the skull by matrix. It has been allowed to remain 

 in this condition, as have also several characteristic shells (Turritella), to serve for 

 purpose of identification with the original of Harlan's figures, and to leave no 

 possible doubt that the series of cervical vertebrae about to be described belong to 

 the same specimen. No mention of these latter has been made in any previous 

 description. They are proved, however, to belong to the type specimen, by the 

 fact that the axis has been fractured in such manner as to leave a portion of the 

 centrum within the ring of the atlas, against which the remaining portion fits per- 

 fectly. The block of matrix in which the verbetrae are embedded without 

 disturbing their natural position is shown in Plate 3. 





