NEW MAMMALS FROM MACHU PICCHU. 

 • Abrocoma ohlativa, sp. nov. 



Plate XXXVIII, figures 1-5. 



Skeletal material referable to a new species of Abrocoma was obtained from several of 

 the burial caves, whole bodies of the little rodents, or portions of them, having been provided 

 to satisfy the supposed requirements of the dead, in accordance with the custom of the 

 Indians. 



Two species of Abrocoma were described by Waterhouse in 1837 (Proc. Zool. Soc. Lon- 

 don, Part V, 1837, page 30), from specimens collected in the mountains of the Province 

 of Aconagua, Chile, by Darwin during the historic voyage of the Beagle. Until the present 

 time, the genus has not to my knowledge been reported from Peru. Its occurrence at 

 Machu Picchu, about 1200 miles from the locality of the type specimens collected by Darwin, 

 adds greatly to the interest the mere skeletal material would possess, without the pelt, and 

 renders a careful comparison with the Chilean species desirable. 



The specific definitions of Abrocoma bennettii and A. cuvieri, in Waterhouse's Natural 

 History of the Mammalia, include important measurements of the type skulls and are there- 

 fore preferable to his original definitions. Several figures of the skull of A. cuvieri are 

 given in the Zoology of the Beagle, Part II, and the type skull of A. bennettii is figured 

 from the lower or palatal view only, in the Natural History of the Mammalia. Fortunately 

 the osteological collection of the Peabody Museum of Yale University affords for comparison 

 an excellent skull from Chile, the original identification of which as A. bennettii was 

 facilitated through the skull being accompanied by the pelt ; hence reference could be had 

 both to cranial and external characters. 



The measurements of the type skulls were given by Waterhouse in inches and lines. I 

 have taken the liberty to translate these into the metric system, in order to arrange them 

 more conveniently in parallel columns with similar measurements of the three skulls of 

 this genus that are now in the Peabody Museum of Yale University, namely, the skull of 

 A. bennettii (Ost. Coll. 1240) and the two skulls (Ost. Coll. 3318 and 3320) from Machu 

 Picchu. Number 3320 is designated as the type of the new species, for which I propose the 

 name Abrocoma oblativa in reference to the pious use by the Indians of the flesh of these 

 little animals. 



From the accompanying table it is apparent that the skull of the new species differs from 

 those of A. bennettii and A. cuvieri not only in its much greater size, but also in certain 

 important proportions of the cranial and facial bones. Comparison of the length-width 

 indices shows the Peruvian skull to be much narrower in form than the others, with reference 

 to the bi-zygomatic diameter. At the same time the width of the interorbital space is both 

 actually and relatively greater than in A. bennettii. The upper tooth rows in the new form 

 are nearly parallel, while in the other species, especially in A. bennettii, the space between 

 the anterior molars is much less than that between the posterior molars. The basioccipital. 

 basisphenoidal and presphenoidal elements are relatively much stouter than in A. bennettii. 



