260 Bulletin American Museum of Natural History. [Vol. XII 



the genus Echimys, and, further, that 1'Echimys dactylin is an 

 aberrant species. 



This was the state of the subject when I. Geoffroy Saint- Hi- 

 laire, the following year, took up the revision of the American 

 Spiny Rats. His conclusions were first published in abstract in 

 1838,* and in full in i84o. 2 This author, aided by the types 

 of nearly all the species named by his father, E. Geoffroy, 3 and 

 first published by Desmarest in 1817, and thirteen skulls, repre- 

 senting in all ten species, was able to throw great light upon this 

 difficult and as yet very imperfectly studied group. His memoir, 

 as published in full in 1840 (/. ^.), opens with an admirable his- 

 torical resume of the subject, followed by detailed analytical and 

 comparative descriptions of both the external characters and the 

 dentition, rendering, with the accompanying plates (eight illus- 

 trating the external features and two the dentition), his memoir of 

 the highest importance as a trustworthy starting point for subse- 

 quent investigators. In matters of nomenclature, however, he 

 naturally followed the customs of the day, disregarding the rule 

 of priority, and adopting methods of selecting types for his 

 genera unfortunately contrary to those required by modern rules 

 of nomenclature. Thus, for example, he considered that the species 

 named chrysurus (as he supposed by Boddaert, and later adopted 

 by various writers, as Shaw, Lichtenstein, and Fischer) should be 

 eliminated " du systeme zoologique comme purement nominate," 

 because it " ne differe pas de V Echimys cristatus" described 

 twenty-five years later. While it is true that the Le'rot a queue 

 doree of Buffon was based on an immature specimen preserved in 

 spirits, received through Dr. Klockner from Surinam, and that 

 Echimys cristatus was based on an adult example from Guiana, 

 neither I. Geoffroy (cf. I. c. y pp. 6, 7, and 49), nor any author who 

 has considered the question, has ever doubted that the two 

 specimens are referable to one and the same species. 



In this paper I. Geoffroy added two new species, and divided 



1 Notice sur les Rongeurs epineux designes par les auteurs sous les noms tf Echimyf. Lonche- 

 res, Heteromys et Nelomys, par M. Isidore Geoffroy Saint-Hilaire. (Presentee a 1' Academic 

 des Sciences le 25 juin 1838.) (Extrait.) Ann. des Sci. Nat., ser. 2, X, 1838, pp. 122-127. 



2 Mag. de Zool., ser. 2, 1840, Mammiferes, pll. xx-xxix, pp. 1-57. 



u Presque tous les originaux des determinations de mon pere existent encore du museum "; 

 and, he adds, " c'estd'apres eux surtout que j'essaierai plus bas la revision de toutes ces especes, 

 en m'aidant de 1'examen de leurs cranes et de leurs dents, et de leur comparaison avec les indi- 

 vidus rapportes depuis au museum par d'autres voyageurs ou decrits par divers naturalistes." 

 Mug. de Zool., 1840 (/. <:., p. 2). 



