MAMMALS OF THE NATUNA ISLANDS I35 



Skull. — The skull is of the same size as that of Pipistrellus pipis' 

 trellus., but the braincase is narrower and more elongate, and the ros- 

 trum is very markedly shorter and broader. The great breadth of the 

 anterior portion of the skull involves also the palate and interpterygoid 

 space, both of which are noticeably wider than in Pipistrellus pipis- 

 trellus. Audital bullae slightly smaller than in the European species. 



7 eeth. — The teeth are essentially as in Pipistrellus pipistrellus., 

 except that the inner upper incisor lacks the small supplemental cusp. 

 Mandibular teeth wider than those of P. pipistrellus. 



Measurements. — External measurements of type : total length 76 ; 

 head and body 41 ; tail 33; tibia 14; foot 6; calcar 10; forearm 

 32.4; thumb 6; second digit 30; third digit 60; fourth digit 53; 

 fifth digit 43 ; ear from meatus 1 1 ; ear from crown 9 ; width of ear 

 9.6 ; tragus (measured in front) 4. 



Ci'anial measurements of type: greatest length 12.4 (12);^ basal 

 length 1 1.8 (11. 6) ; basilar length 9 (9) ; zygomatic breadth 8.4 (8) ; 

 least interorbital breadth 3.2 (3.2) ; greatest length of braincase 8 

 (7.6) ; greatest breadth of braincase above roots of zygomata 6.6 

 {^^.^) ; mandible 8.8 (8.4) ; maxillary toothrow (exclusive of incisors) 

 4.2 (4.2) ; mandibular toothrow (exclusive of incisors) 4.8 (4.8). 



Specimens examined. — Six (in alcohol), all from the type locality. 



Remarks. — I am unable to identify this bat with any described 

 species. Externally it is practically identical with Pipistrellus 

 fipistrellus except that the color, so far as can be judged from speci- 

 mens preserved in alcohol, is more blackish. Internally it is readily 

 distinguished by the characters of the skull and teeth. From Pipis- 

 trellus abramus it differs externally in smaller size, narrower ears, 

 and in the absence of any unusual development of the penis. The 

 incisors differ from those of P. abramus in the same manner as from 

 those of P. pipistrellus. 



HIPPOSIDEROS LARVATUS (Horsfield). 



Two specimens (one in alcohol) were collected on Sirhassen Island, 

 June 6 and 7, 1900. 



RHINOLOPHUS AFFINIS (Horsfield). 



One badly damaged specimen from Bunguran appears to be refer- 

 able to typical Rhinolophus aff,ms. The forearm cannot be meas- 

 ured, but the third finger is 75 mm. in length. Tibia 21, foot 10.4, 



1 Measurements in parentheses are those of an adult skull of Pipistrellus 

 pipistrellus from Switzerland. 



