AitT. 14. MARYLAND FOSSIL POEPOISE KELLOGG. 5 



From the type caudal of Zarhachis fiagellatoi^ and the specimen 

 described in the following pages, the following characters have been 

 derived which are considered diagnostic of the genus. 



Diagnosis. — General architecture of top of skull as in Lipotes 

 and resembling Platanista in certain details, but with a long attenuate 

 rostrum comprising more than five-sixths of the total length of the 

 skull. The beak is neither bowed upward, nor bent downward, but 

 is approximately straight; the basicranial axis presumably is not 

 strongly bent downward from the axis of beak. The internal por- 

 tion of the proximal extremity of the premaxilla is thin and plaie- 

 like as in Lipotes and Platanista^ and does not form a convex raised 

 anterior border to the nasal apertures as in Inia. For more than four- 

 fifths of the total length of the rostrum the raised convex portions 

 of the premaxillae are closely appressed and parallel each other to 

 the tip of the rostrum, thus forming the roof for the mesorostral 

 gutter. The presphenoid rises to the level of the premaxilla as in 

 Lipotes. The maxillae posterior to the maxillary notches expand 

 laterally, sheath the internal faces of the thick up-built supraorbital 

 processes of the frontals, and partially roof over the temporal fossae. 

 The zygomatic process of the squamosal is in contact with the post- 

 orbitial projection of the supraorbital process of the frontal. The 

 external pterygoids extend forward beyond the level of the maxil- 

 lary notches and conceal the palatines. The nasal passages are situ- 

 ated anterior to the level of the anterior margins of the squamosals. 

 There is a deep groove between the squamosal and frontal bones into 

 which the foramen ovale opens. The total number of teeth exceeds 

 three hundred. The first tooth on either side of the rostrum is con- 

 siderably larger than any of the following teeth. The enamel crowns 

 of the teeth are ornamented with fine longitudinal striae. The roots 

 are slightly thickened. The ankylosed symphysial portion of the 

 mandibular ramus equals eight-elevenths of the total length of either 

 mandible. 



* The periotic bone bears a close resemblance to that of PJatanista. 

 The most important differences consist of a more elongated internal 

 acoustic meatus, and a wider interval between the foramen singulare 

 and the cerebral aperture of the facial canal. The tympanic 

 bone also is very similar in general features to that of Platanista. 



The hyoid bones differ from those of Platanista and agree in some 

 respects with those of Inia. They consist of a central portion (basi- 

 hyal) with large, expanded, subcrescentic wings (thyrohyals) and a 

 pair of short, anterior, conical projections (ceratohyals). The stylo- 

 hyals are free, elongate, and slightly curved. 



The atlas is free and possesses both upper and lower transverse 

 processes. The greatest length of the atlas is about one-half of the 

 greatest width across the anterior articular facets, A pair of large 



