the Musk-Bat of the Aatilhs. 387 



Mer/alomys pilorides. Oryzomys palustris. 



Ten-estrial. Amphibious. 



a. Ears entirely naked both a. Ears hirsute both sides, 

 sides, largely overtopping the fur, small, little overtopping the fur, 

 without tuft of hairs on the con- with a fluffy tuft of hairs on thi; 

 cavity. concavity. 



b. Hind feet very long, but com- b. Hind feet very long and large 

 pressed, with parallel short and (as in Fiber), with obliquely set 

 stout toes. long and slender toes. 



c. No trace of web at the base c. A slight but evident web at 

 of the toes. the base of all the toes. 



These three characters are quite sufficient to necessitate 

 the separation of tlie two genera. That being granted, I shall 

 willingly acknowledge that very likely Megalomijs represents 

 the terrestrial type of Oryzomys. As regards the superciliary 

 crests of the skull, the anteorbital foramen, and even the 

 structure of the teeth, I shall prove elsewhere that they 

 have nothing peculiar to permit of uniting the two genera, 

 but are characters of all the largest Murida3 or of many of 

 the American Cricetinte. 



The genus Megalomys includes at the present time three 

 species : — (1) Mas pilorides, the type of the genus ; (2) Ory- 

 zor.iys lucice, Major iloc. cit.) ; and (o) the fossil species (of 

 Barbuda) referred to, but not described, by Dr. Forsyth Major 

 in the above-mentioned note. 



II. — There remains still to elucidate a double question of 

 nomenclature — (I) The genus of which Mas pilorides is the 

 type might retain the name Megcdomys ; (2) the species must 

 be called ^^ pilorides, Desmarest, 1826," as I have admitted, 

 or be known by the name of " piloris, Zimmermann, 1777," 

 as Dr. Forsyth Major wishes, or else^ again, as Mr. J. A. 

 Allen * suggests. 



First, it must be remembered that Laurillard, in 1818, 

 created under the name ^^ Meyamys''^ a genus of fossil 

 Rodentia which includes the largest mammals of this ordar at 

 present known. Now, this name of Meyamys is wrong as an 

 abbreviation of ^^Meyalomys,^'' the only name correctly formed. 



In agreement with the rules of nomenclature prescribed by 

 the International Zooldgical Congresses, " Meyamys " ought 

 to be rectified into " Megalomysj^ and, consequently, Meya- 

 loriiys (Trouessart, 188J), given to Mas pilorides, is not 

 available, as preoccupied, and must be altered. 



Accordingly I propose to substitute for Meyalornys (Trt., 



» IkiU. Amer. Mus. Xat. Hi^t. xvi. 1902, pp. 13, 20. 



28* 



