

168 A NEW FOSSIL PORPOISE FROM MARYLAND. 



oblong in form, each about 19 mm. wide and 22 mm. high, with a concave anterior 

 surface and flat superior surface. They are nearly vertical in position, as in 

 Phoccena, and rest on the upper border of the narial septum, which extends little, or 

 not at all, above the level of the superior nares. The nares, taken together, are 

 triangular in outline, with a maximum breadth posteriorly of 34 mm. The narial 

 septum is low and does not extend backward as far as the premaxillae, nor upward 

 beyond the level of the nares. The mesethmoid extends but very little beyond 

 the nares, and anterior to it the premaxillae are widely separated, as in Sotalia 

 and Steno, so that the deep vomerine trough is plainly visible. 



The posterior exposed border of the frontals at the sides of the vertex is very 

 narrow, having an antero-posterior breadth of about 5 mm. At the vertex, the 

 space between the supraoccipital and nasals, occupied by the frontals, appears to 

 be about 27 mm., antero-posteriorly. This anterior median extension of the 

 frontals is not elevated above the adjoining bones. 



Lateral Aspect (PI. XVII, fig. 3). — The most noticeable features of the side of 

 the skull are the large size of the orbit, and the thinness of the frontal and max- 

 illary plates above the same. The anteorbital region is not elevated or thickened. 

 The postorbital process is triangular, slender, and elongated. The temporal 

 fossae were apparently of large size, but the skull is too much distorted in this 

 region to permit a determination of their form. 



The zygomatic process, seen from without, is oblong, elongated, and truncated 

 at the extremity, having about the same form as in Sotalia. The postglenoid 

 process is moderately long and curved forward. 



Inferior Aspect (PL XVII, fig. 2) .—The surface of the palate is convex prox- 

 imally. The vomer is visible somewhat posterior to the middle of the rostrum as 

 a rather broad, elliptical area about 43 mm. long and 7 mm. broad. 



On either side of the vomer, a foramen is visible in the maxillae. From these 

 foramina grooves extend forward in the median line, and together with the 

 shelving internal border of the maxillae cause the palate to be quite deeply 

 concave in this place, as in the ziphioids. On account of imperfections, it is 

 impossible to determine how much of the distal portion of the palate is formed by 

 the premaxillae. These bones appear to be broad and inclined inward near the 

 extremity of the rostrum, but the fine of demarcation which is visible may be 

 a fracture rather than a sutural line. 



The palatine bones are not clearly marked off from the adjacent portion 

 the maxillae, but appear to differ from the form found in the majority of recent 

 delphinoids, in that the anterior margins of the two bones do not diverge from 

 the median line, leaving a V-shaped area between them, but are in contact 

 nearly to the most anterior point, while laterally there is a deep emargination on 

 either side. A depression occupies a large portion of each palatine bone near 

 the median line posteriorly, with another, less deep, external to it. These 

 bones, therefore, resemble those of Eurhinodelphis , as shown in the figures 

 Professor Abel, 1 rather more closely than those of any other genus. 



1 M6m. Mus. Roy. Hist. Nat. Bek., I. 1901. ri. ft. TT lQn9 nl 13 



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