200 VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 



Length of three crowns m. .0048 ; length exserted portion of inferior incisor 

 m. .007 ; transverse diameter of inferior incisor at point of issue m. .0023. 



From the extent of the worn surfaces of the molars, the animal described is 

 adult. The second ramus is of the same size ; the dental series is complete, and 

 the teeth are worn so as to present a dentinal area surrounded by a thin margin of 

 enamel. The outlines of the teeth are like those of the first specimen. 



As compared with S. panolius Cope, the species is larger, and differs in the 

 form of the m. 1, as much as in the case of S. Iiudsonins. 



CASTOR Linn. 

 Castor fiber Linn. 



Castor canadensis Kuhl., Baird, Mamm. N. Amer., p. 3r>5. 



A left mandibular ramus, lacking the condyle and angle, of this species was 

 obtained by Mr. Mercer in excellent preservation. The dental series is nearly 

 perfect. The general proportion is quite as in the existing beaver, but a difference 

 in the molar teeth is observable. This consists in the greater anteroposterior diameter 

 of the premolar. In the typical beaver, the anteroposterior diameter of the -last 

 true molar is equal to that of the first premolar. In the present species the former 

 is about three-quarters ' the latter, the length of the former reaching only to the 

 anterior transverse loop of the latter. The posterior column of the last true molar 

 has a smaller transverse diameter than the anterior column of the same. In a 

 considerable series of beaver skulls, I find one in which the proportions of the teeth 

 approach very closely to the Port Kennedy specimen. 



Measurements. 



mm. 



Depth of jaw at coronoid process ; 50 



Depth of jaw below m ¥ ; 17 



Length of molar series ; 34 



tv f n / • t r \ ( anteroposterior; 10.5 



Diameters ol inn. 1 (grinding lace { , P r 



1 v& 1 transverse ; b.5 



-p.. i / • j- r \ (anteroposterior; 8 



Diameters m. 1 (grinding lace) { , L r- r 



Vo ° ' \ transverse ; t .5 



Long diameter grinding face m. 3 ; 6.5 



Three superior molars were found subsequently and at another part of the 

 excavation. They are the m. 1 of opposite sides and an m. 2. They do not differ 

 from those of the common beaver. 



ZAPUS Coues. 

 Zapus hudsonius Zimm. 



Jaculus hudsonius Baird, Mamm. N. Amer., p. 450. 



One ramus mandibuli with incisor and second molar preserved. The latter 

 nearly resembles the figure in F. Cuvier's Dents des Mammiferes and the ramus is 

 about the size of that of the existing jumping mouse. Nevertheless, in lack of 

 specimens of the cranium of the latter, I am unable to determine its specific 

 relations. 



