MARYLAND GEOLOGICAL SURVEY 49 



Occurrence. — St. Mary's Formation. Chesapeake Bay near Point- 

 no-Point (the specimen was dredged up from the bottom of the bay) 

 Collection. — Johns Hopkins University. 



The following characters of the genus Siphonocetus (Eschrichtius) 

 were given by Cope in 1869 : 



" Characters of the mandibular rami. Much compressed, outer face little 

 convex; superior margin a narrow ridge without truncation; with a series 

 of foramina on each side; the inner extending for a very short distance only; 

 no marginal groove; inferior edge narrow. 



Very large 8. cephalus. 



Upper edge broad, with oicter series of foramina, and meeting inner edge 

 at a right angle, which is the highest line, and with inner series of foramina 

 just below it; most convex externally. 



Large S. prisons. 



Upper edge broad behind only, and there bearing only the inner series of 

 foramina. Elsewhere with a median ridge and rows of foramina below on 

 each side; much decurved; less convex externally. 



Medium S. expansus. 



Upper edge nowhere broad, and with a deep or shallow groove below it on 

 the inside; less decurved; less convex externally. 



Small S. pusillus. 



To this list may be added the following brief analysis of the char- 

 acters of S. clarlcianus. 



Upper surface a low ridge formed by the meeting of the outer and 

 inner faces at almost a right angle; section of jaw lenticular; inner 

 and outer faces convex, the external the most so; outer series of fora- 

 mina large; inner series double, the superior are the smallest and 

 situated quite near the superior edge. 



Genus ULIAS Cope. 



" Char. gen. Mandible with the gingivodental canal open throughout 

 most of its length, closed only near its apex. Gingival foramina repre- 

 sented by a few orifices on the alveolar border near the distal extremity. 



" This form is of much interest as representing in adult life a stage 

 which is transitional in typical Balsenidse. The alveolar groove is 

 continuous with the dental canal, and is permanently open. It is 

 probable then that this genus possessed teeth during a longer period 

 than the existing Balsenidse, and that they were retained in place by 

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