NO. 5 MAMMALS FROM DOMINICAN REPUBLIC MILLER 9 



Rio San Juan. — Rostrum with incisors and first two cheekteeth, i ; 

 fragments of premaxilla with incisor, i ; mandibles, 30; odd teeth, 25. 



Kilouicter 2 site. — Fragments of palate, 2; complete mandible, i ; 

 fragments of mandibles, 2; odd teeth, 3. 



Kilometer 4 site. — Fragment of palate, i ; mandibles, 6 ; odd teeth, 5. 



PLAGIODONTIA HYLiEUM Miller 

 Plate I, fig. I 



Railroad cave. — Imperfect skulls, 2 ; right side of rostrum with 

 incisor, i ; palate lacking m^ of both sides, i ; mandibles, 4. 



Sa>i Gabriel (owl deposit). — Mandible, i young; left lower incisor, 

 adult, I, 



The specimens now at hand enable me to confirm the original 

 diagnosis of Plagiodontia hylceuni and also to add two important 

 characters. 



That the living animal is decidedly smaller than Plagiodontia cedium 

 is abundantly shown by comparison of the skulls and jaws from 

 Guarabo and the south shore of Samana Bay with the remains of the 

 larger animal collected on the Samana peninsula and near Monte 

 Cristi. The 12 jaws of P. hylceum whose measurements are given in 

 the original description range from 51 to 55.2 mm. in length. An 

 additional specimen from the Railroad cave is slightly imperfect but 

 its length must have been about 51 mm. One mandible of P. (rdiuui 

 from San Pedro de Macoris was recorded as slightly more than 62 mm. 

 long. Unfortunately most of the jaws from the Samana Peninsula are 

 injured at one end or the other, so that their length cannot be de- 

 termined, but two from Anadel give measurements of approximately 

 61 and 62 mm. A measurement that is more useful, because mandibles 

 are seldom so badly broken that it cannot be taken, is the depth from 

 the alveolar margin to the protuberance made by the root of pm4. 

 In 10 jaws of Plagiodontia <Edium this depth averages 16.3 mm. with 

 extremes of 15.4 and 17.4 mm. In an equal number of jaws of the 

 smaller animal the average depth is 13.2 mm., the extremes 12.2 and 

 14.0 mm. Similarly obvious and constant is the dift'erence between 

 the alveolar length of mandibular toothrow in the two species. Ten 

 specimens of each give the following averages and extremes : P. 

 hylceum, 19.8 mm. (18.6 to 20.6 mm.) ; P. cedium, 24.2 mm. (23.2 to 

 25.4 mm.). 



The most important character brought to light by the new material 

 is, however, the difference in relative length of the first and second 

 maxillary cheekteeth. In Plagiodontia hylceum the crown length in- 



