NO. 12 MAMMALS FROM CUBA AND SANTO DOMINGO MILLER 5 



2; humerus (right) i8, (left) 8; radius (right) 2, (left) 2; ulna 

 (right) 2, (left) 2; innominate (right) 7, (left) 3; sacrum 3; femur 

 (right) 28, (left) 36; tibia (right) 28, (left) 25. 



San Lorenzo: 2 left lower jaws. 



On the basis of the present material, even after comparison with 

 the numerous Porto Rican specimens kindly lent me by Dr. Allen, 

 I am unable to find any character by which to distinguish the Santo 

 Domingan Isolohodon from that of the neighboring island. This 

 animal is by far the most abundantly represented of the mammals 

 found in the Macoris deposits. It must have been common at San 

 Lorenzo as well, for two of the three jaws which Gabb collected 

 there and I recorded as Plagiodontia turn out to be Isolohodon. One 

 of these specimens lacks all of the teeth while in the other the first 

 and second teeth are lost and the third and fourth are broken away 

 to below the alveolar level. Under these circumstances and before 

 I had seen the description of Isolohodon I overlooked their true 

 characters. Among the bones found at San Lorenzo by Dr. Abbott 

 this genus is absent. 



The tooth structure in Isolohodon is essentially like that of 

 Plagiodontia except that the upper premolar retains a small antero- 

 external reentrant fold, the reentrant folds in each of the molars 

 and the main folds in the premolar are opposite, their tips coming 

 in contact at middle of crown, and in the lower teeth the outer re- 

 entrant angle is much deeper than those of the inner side. The 

 cement in the teeth of Isolohodon is of a peculiarly open structure, 

 showing conspicuous horizontal striation. 



PLAGIODONTIA AEDIUM F. Cuvier 



(Plate I, fig. 4) 



Macoris: 15 specimens (representing probably about 6 indi- 

 viduals) : lower jaw (right) i, (left) i ; humerus (right) 2, (left) 

 i; innominate (right) i, (left)i; femur (right) 2, (left) 4; tibia 

 (right) I, (left) i. 



San Lorenzo: 8 specimens (representing probably 3 individuals) : 

 anterior half of skull with complete dentition of right side, i ; left 

 lower jaw, i ; innominate, 3 ; femur, i ; tibia, 2. 



Measurements: No. 217112 (San Lorenzo) : bregma to front of 

 premaxillaries, 53.6; length of frontal along median suture, 26.6; 

 least interorbital breadth, 19.0 ; breadth of rostrum across upper 

 rim of premaxillaries, 12.8; diastema, 17.2; maxillary toothrow 

 (alveoli), 21.0; crown of m\ 5.2x4.8. No. 217126 (Macoris): 



