1908.] DR. KNUD ANDERSEN ON BATS. 245 



rounded (this would be, so far as this character is concerned, 

 Rehn's A. planirosti^is) ; the other extreme in the same series of 

 skulls (one specimen) : m^ long antero-posteriorly, especially in its 

 lingual half, antero-internal angle very sharp, practically rect- 

 angular (this would be Rehn's A . hercules) ; in the three remaining 

 skulls the tooth is intermediate in shape. As to p^ and m,, I 

 must confess I do not quite understand Rehn's description, unless 

 " second lower premolar " is a lapsus for first lower molar, and 

 " first lower molar " for second lower molar ; there is, of course, 

 no " dentate ridge " on the postero-internal border of p^ in any 

 bat of the genus Artibeios, but there is on mj, and the absolute 

 size of the cusps of this dentate ridge (cusps 2 and 3) is subject 

 to notable individual variation. — ^When entering upon such 

 minute details as here under consideration, we shall scarcely find 

 two skulls of A. p. fallacc (or any other form of A. planirosti'is) 

 precisely alike ; we have passed from the characters useful for a 

 specific or subspecific discrimination to the field of individual 

 variation, and, judging from what 1 have seen in a large series of 

 skulls of A. p. fallckv, I should think it highly probable that if 

 Rehn extracted the skull of his second specimen of A. hercules, 

 he would find the form of the lingual portion of p* or m^ or both 

 of them slightly difiering from that of the corresponding teeth in 

 the single skull described. 



It is, of course, quite possible that Peruvian individuals dififer 

 in some minor details (or some average characters) from the 

 Guianan A. p. fallax ; for the present it is at least certain that 

 there is not in Rehn's description one single character by which 

 A. hercules can be discriminated from A. p. fallax. 



Elliot's Uroderma validum, 1907. — Type locality : Cayenne. 

 From the figures of the skull, the description and measurements, 

 clearly an A. p. fallax. Elliot has apparently been unaware of 

 the fact that the type of U. validitm (Cayenne) is practically a 

 topotype of A. jJ. fallax Peters (Guiana). 



Artibeus hirsutus K, And. 



1906. Artibeus hirsutus Knud Andersen, Ann. & Mag. N. H. (7) xviii. p. 420 (1 Dec. 

 1906). — Type locality: Michoacan, Mexico. 



Diagnosis. — Like a small form of A. planirostris (though 

 averaging still smaller), but tibia and interfemoral densely haired, 

 and colour of fur of upper side of body in adults drab with a 

 silvery tinge. Maxillary tooth-row 9 -5-1 0-4 mm. ; forearm 53"7- 

 59*7 mm. 



Skull and teeth. — In the skull and teeth there is 210 essential 

 diiference between A . hirsutus and a small form of A . planirostris, 

 f. i. A. p. trinitatis ; the rostrum of the skull may, perhaps, 

 average somewhat narrower. — Molars |^, as in A. concolor and 

 planirostris, and as in these species the presence of the small m^ 

 is almost constant. Eight skulls of A. hirsutus have been 

 examined ; in two ( $ ad., teeth unworn, Michoacan, U.S. N. M. 



