284 MR. J. O. WESTWOOD ON NYCTERIBIA. 
lations, let us examine the statements of authors as to the structure of this part of the 
body in the previously recorded species of the genus. 
Hermann describes three kinds of individuals. The first, to which he applies the 
specific name of Vespertilionis, has the abdomen obovate, convex, and attenuated behind, 
with the terminal segment entire and rounded at the extremity, and furnished beneath 
with a pair of incurved styles. He also describes minutely another organ, which, upon 
compression, ‘‘sort entre les deux avant-derniers anneaux,”’ of a fleshy substance, ter- 
minated by two small oval lobes, and from the extremity of which, upon further pressure 
being applied, another organ was protruded, furnished beneath with a curved scta. The 
second kind of individuals were regarded by him as specifically identical with the former, 
differing only in having the last segment deeply emarginate and simple: the body also 
seemed larger, and the legs shorter. In this species the cilia of the extremity of the 
basal abdominal segment are continued along the upper side of this part of the body as 
well as beneath. Now it is evident that the individuals first described were males, not 
only from the articulation of the abdomen, but from the possession of an exserted mas- 
culine apparatus ; but the other individuals (of which Hermann had only two old dried 
specimens), in the simple and emarginate character of the abdomen, seem to approach 
the females of Nyct. Latreillii subsequently described: and it is to be observed that 
Hermann does not state that their abdomen was articulated like that of the former, but 
merely points out the characters in which they were observed to differ. Neither does 
he give any opinion as to the sexes of his insects! His third kind of individuals, 
specifically named biarticulatum, precisely agree with Montagu’s species, described by 
Dr. Leach under the trivial name of Hermanni, having a pair of exserted styles at the 
superior extremity of the abdomen. Liatreille seems entirely to have overlooked Her- 
mann’s description of the latter insect in his account of the structure of the genus, 
assigning to Hermann’s second kind of individuals a character not stated by Hermann, 
namely, that of the abdomen being eight-jointed, and giving the biarticulatum as the 
male of his Nyct. Vespertilionis. Dr. Leach, evidently taking his characters from his 
Hermanni, thus describes the abdomen: ‘‘ In utroque sexu 8-articulatum.—Fcemine ? 
segmento primo dorsali producto, segmenta quatuor sequentia tegente ; segmento ultimo 
stylo apice setigero instructo ;—Maris? segmento ultimo majore.” And his figure of 
the supposed female of his Hermanni represents an insect with a large elevated and 
produced basal abdominal segment, the remainder of the abdomen, being the smaller 
portion, appearing inarticulate, and terminated by two long recurved piliferous diverging 
styles: the figure of the other sex has the abdomen six-jointed, the last joint being large 
' If the abdomen in this second kind of individuals were really articulated, as in the former, I should feel little 
hesitation in regarding them as the males, probably of a different species, in which, from the dried and shrivelled 
state of the specimens, the male organs had become closely applied to the under surface of the body, and the 
terminal segment, for the same reason, had become emarginate. 
