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A NEW FOSSIL PORPOISE FROM MARYLAND. 169 



At the posterior end, the palatines present a deep transverse channel, which 

 represents the base of the pterygoid sinus. The pterygoid bones themselves 

 are too defective to permit a determination of their original form. The region 

 of the posterior nares is also much fractured and distorted. 



The descending wings of the basioccipital, or that portion against which 

 the tympanic bones rest, are peculiar in that they are traversed by a strong, 

 inferior ridge, directed obliquely outward and backward. The area behind the 



dg 



This conformation is unlike any which I have observed 



other forms, and may be regarded as characteristic of the species. The free, 

 inferior extremity of the exoccipital extends considerably below that of the 

 wings of the basioccipital, while in recent delphinoids the two are about on a 

 line, or else the basioccipital is the longer. The free extremity of the exoccipital 

 above mentioned, seen from below, presents a semicircular outline, and a conca\ < 

 surface. 



The condyloid foramen is situated posterior to the deep channel between the 

 exoccipital and the descending wings of the basioccipital, as in Eurhinodelphis, 

 instead of in the bottom of the channel itself, as normally in recent delphinoids. 



The postglenoid process of the zygomatic is very prominent, and is cut off 

 from the portion of the zygomatic which adjoins the exoccipital by a very distinct 

 groove. ^ The glenoid fossa is comparatively narrow and elongated. 



The inferior surface of the orbital plate of the frontals is broad, smooth and 

 only moderately concave. The anterior basal portion of the malar consists of 

 an almond-shaped bone, broad and thin toward the median line, and narrower 

 and thicker at the outer free extremity where it is inserted between the frontal 

 and maxilla, and forms the outer portion of the maxillary notch. The posterior 

 margin of this bone, which forms the antero-internal portion of the roof of the 

 orbit, is convex backward. The styloid portion of the malar appears to be 

 inserted at the extreme anterior angle of the expanded portion, but as the sutural 

 lines are not distinct, the latter may extend somewhat beyond the former anteri- 

 orly. As already mentioned, the malar forms the whole of the outer wall and 

 base of the maxillary notch, the maxilla stopping just short of the notch anteri- 

 orly. The styloid portion of the malar which remains is about 23 mm. long, 

 very slender and tapering. The posterior portion may have been cartilaginous. 



The basal portion of the malar above described may, of course, represent the 

 lachrymal, as it does in recent delphinoids, but there is no clear separation 

 as there is in the ziphioids. This is of importance because, as is well known, the 

 lack of a distinct lachrymal bone is one of the characters of the family Delphinidae. 

 A noticeable feature of this skull, when viewed from below, is the short 

 distance between the last maxillary tooth and the base of the maxillary notch, 

 which is but 22 mm. 



Posterior Aspect (PL XVIII, fig. 1).— As already remarked, the skull has been 

 much distorted by pressure from above, the supraoccipital having been fractured 

 just above the condyles, and the top of the skull pressed down, so that the roof 



