1908.] DR. KNUD ANDERSEN ON BATS. 233 



7'ostt'is and hirsutits. A. concolor is externally not very inferior 

 in size to a small A. hirsidus or A. planirostris trinitatis; the 

 forearm in the only specimen examined of A. concolor measures 

 50 mm., in the smallest A. hirsutus 53-7 mm.; but the length 

 of the maxillary tooth-row is in concolor only 7*2 mm., in the 

 smallest-toothed A. hirsutus 9*5 mm. A comparison with 

 A. planirostris shows a similar contrast. — In structure the teeth 

 of A . concolor do not differ from those of A . planirosti'is and 

 hirsutus. 



Skull. — Rostrum (probably owing to small size of teeth) rela- 

 tively much shorter than in A . hirsutus or planirostris. The ratio 

 between the length of the i-ostrum (from front of sagittal crest to 

 front of alveokis of a median incisor) and the length of the brain- 

 case (from front of sagittal crest to median posterior point of 

 lambdoid crest) is in concolor 68 : 100, in hirsutus find 23la'nirostris 

 83 : 100; or, expressed in another way, the length of the nasal 

 region, from front of sagittal crest to front of nasal bones, is in 

 A. concolor equal to the least interoi'bital width of the skull, in 

 hirsutus and p)lanirostris equal to 1| this width. The rostrum 

 in A. concolor is a trifle less depressed than in hirsutus and 

 planirostris, but the difference in this respect is inconspicuous. — 

 The short rostrum makes, of course, the total length of the 

 skull much smaller : in concolor 22*4, in the shortest-skvilled 

 hirsutus available 26'8 mm., although, as mentioned above, the 

 animal in external dimensions is only a trifle larger than concolor. 

 The difference in the length of the foreai-m, between concolor and 

 a small hirsutus, is only 3"7 mm., but in the leng-th of the skull 

 4"4 mm. — In every other respect the skull of concolor is similar 

 to that of j)lanirostris and hirsutus. 



Nose-leaves. — Front margin of hoi'seshoe free ; both front and 

 lateral margins quite plain (not crenulate). It remains to be 

 ascertained if these characters are perfectly constant (compare 

 the individual variation in A. planirostris, hirsutus, &xid jamai- 

 censis). 



Tixtgus. — 7 or 8 sharp, but short, serrations on the upper half 

 of the outer margin, above the median projection ; the highest 

 number of serrations found in any other species of Artibeus is 5. 

 A large series of A. concolor will, no doubt, show some variation 

 both in the number and shape of the serrations. 



Hairing on limbs and interfemoral. — Essentially as in A . p>lani- 

 rostris : upper side of proximal half of forearm, upper side of inter- 

 femoral (the extreme posterior margin excepted) and of femur (the 

 distal part excepted) densely haired. 



Colour. — Upper side from shoulders backward yellowish brown 

 (rather browner than Ridgway's " wood-brown ") ; base of hairs 

 almost ecru-drab. In front of the shoulder region the darker 

 hair- tips are sLoi-t or altogether wanting", exposing the white 

 or yellowish-white ground-colour of the fur. Under side light 

 greyish drab. Supraorbital stripes distinct, infraorbital stripes 

 almost obsolete. There seems to be no light margins to the ears. 



