644 SCIENTIFIC RECORD FOR 1884. 



The dentition of the Capyhara. — The Capybara is distinguished by a 

 very remarkable dentition which has impelled some naturalists to recog- 

 nize it as a peculiar family type — the Hydrochoeridse. The milk-teeth 

 have been lately examined by Professor Flower. The little animal, 

 eight days old, had just the same number of teeth as the adult. " The 

 incisors and four molariform teeth were all present and in an equal state 

 of development. A small jjortion of the surface of each, including the 

 posterior molar, has been already abraded by wear. The molar teeth 

 show the same form and pattern as in the adult, being each divided by 

 deep lateral grooves into distinct lobes corresponding to those of the 

 full-grown teeth. They are, however, all very much smaller, the length 

 of the whole series in the upper jaw being 30 millimeters instead of 72 

 as in the adult. They evidently represent the narrow apical portion of 

 the permanent teeth, which, as growth proceeds, wears off, and they are 

 not in any case milk-teeth. As the first of the series, or premolar, is as 

 fully developed as the one which follows it (or first true molar) it must 

 either have no predecessor, or one which has disapjieared at an early 

 stage of intra-uterine life." [Proc. Zool. 8oc. London, 1884, pp. 252, 253.) 



A new generic type related to the Musl'-rat. — A naturalist would scarcely 

 look for a new generic type of mammals as large as a rat in any part of 

 the United States, and yet such a form was obtained last yeai- by the 

 National Museum aud described by Mr. Frederick W. True, the curator 

 of mammals. The specimens were obtained at Georgiana, Fla., by 

 Mr. William Wittfield. The animal resembles an ordinary musk-rat in 

 general appearance, but has neither the compressed rudder-like tail nor 

 the large webbed hind feet and bent toes characteristic of the musk-rat. 

 It looks, indeed, in the words of Mr. True, '' like an overgrown and 

 dropsical'house-rat, and was at first entered in the catalogue of the 

 Museum," by his assistant, "as a doubtful species of that genus." A 

 closer examination, however, demonstrated that it was very distinct not 

 only from any BIus, or the musk-rat, but from any other known mammal. 

 It has the " general form and color," as well as the " head, eyes, and fore- 

 legs," characteristic of the musk-rat, but the hind limbs are less than 

 twice the length of the fore-feet and have "straight slightly webbed 

 toes and naked soles;" the tail is round and very thickly covered with 

 duli-brown hair, through which the scales which encase it are apparent. 

 The length of the head aud body is 20.2 centimeters, and that of the 

 tail 12,7 centimeters ; the hind-feet (without the claws) are 3.9 centi- 

 meters long. 



No particulars have been received respecting the habits of the animal, 

 but, in Mr. True's opinion, " the slight webbing of its toes, and their 

 unbent condition, taken together with the rounded tail, would lead one 

 to prophesy that it is not so thoroughly aquatic as the ordinary musk- 

 rat, probably no more so than many of the field-mice." The name 

 Xeofiber Alleni has been given to the new Murid. {Science, iv, p. 34.) 



