NYCTINOMUS TENUIS. 
The Nyctinomi, as their name denotes, feed at night During my residence 
on the hills of Prowoto, which have already several times been mentioned in these 
Researches, their pursuit afforded me an occasional amusement. Although they are 
also found in other parts of Java, they are peculiarly abundant on these hills, which 
are covered with a luxuriant vegetation, and afford a plentiful supply of their 
favourite food. They appeared after sunset, while the light was still sufficient for the 
purpose of distinguishing objects clearly. Observing them almost uniformly, and 
in quick succession to direct their flight along the hedge, which surrounded a village 
in which I had my abode, I watched them in this situation, and readily caught 
them with a large net, which was used in the pursuit of Lepidopterous Insects, 
By this means I obtained them in great numbers, and selected those that were 
required for my collections, 
I shall conclude this article with a few concise comparative remarks on the 
various species of Nyctinomus hitherto discovered, and with an enumeration of their 
specific characters. The Nyctinomus tenuis exhibits very strikingly the characters 
which afford to the Nyctinomi generally a very peculiar physiognomy ; but the 
narrowness of its wings, and the slendemess of its tail, distinguish it clearly from 
the other species. For a comparison with the Nyctinomus Egyptiacus, the copious 
description of M. Geoffroy, accompanied by an accurate and beautiful figure, in the 
" Description de TEgypte," afford the most ample materials. From these it appears, 
that the ears in the Egyptian species spread more in a lateral direction, and 
that the interfemoral membrane is deprived of muscular fibres. It has likewise 
a very different colour, being reddish brown above, and brown underneath. Further, 
I have not observed in M. Geoffroy 's figure, so distinctly as occurs in our species, 
the short stiff bristles which are scattered profusely on the sides of the face, and 
the dots in the membrane of the wings, on each side of the body. By possessing 
these, the Nyctinomus tenuis exhibits a great resemblance to Commerson's species, 
the JtfycUnomede Port-Louis; but the latter is considerably smaller ; the membrane 
of the body is described as " nuda ad sternum" (Hermanni Obs. Zool, p. 19,) and 
the interfemoral membrane envelopes two-thirds of the tail. The Nyctinomus 
of Bengal agrees with our species in possessing the transverse muscular fibres of 
the interfemoral membrane ; but it is distinguished by a more robust habit, by a 
thick, round, fleshy tail, and by a very short thumb. 
Having above mentioned a second species of Nyctinomus from Java, for which 
I have proposed the name of dilatatus, I shall now add the distinguishing characters, 
and subjoin those of the other species in succession. 
