MR. J. O. WESTWOOD ON NYCTERIBIA. 277 
Served in spirit; to J. F. Royle, Esq., who has permitted me to examine a smaller 
Indian species collected by himself; and to J. F. Stephens, Esq., who has granted to 
me the loan of his specimens of Nyct. Hermanni and Nyct. Latreillii, which he obtained 
from Dr. Leach himself. I have likewise examined Dr. Leach’s three specimens of his 
Nyct. Latreillii, three of his Nyct. Hermanni, a specimen apparently of the latter species 
received by him from Bonelli, and the original specimen of his Nyct. Blainvillii, all con- 
tained in the cabinets of the British Museum. 
As Colonel Sykes’s specimens have afforded the clue to the determination of the 
sexes, in consequence of their being in different stages of gestation, and as they are 
of a large size, and moreover preserved in spirit, thus affording the means of a more 
satisfactory examination, I propose, in the first place, to notice their structure in detail, 
comparing it with that of the already described species, and endeavouring to clear up 
the various difficulties existing in the works of previous observers; in the second, to 
describe more concisely the structure of the other species which I have myself examined ; 
and in the third place to attempt a synopsis of the various species. 
The three individuals of Colonel Sykes’s East Indian species, which I have inscribed 
with his name, vary somewhat in size, according to the degree of gestation, from 
2 to 21 lines in length, and about 7 lines between the extremities of the anterior and 
posterior legs when stretched out. 
The body is of a crustaceous texture, with the exception of the abdomen and upper 
teguments of the thorax, which are of a leathery nature. 
The head (contrary to the character given of the family by Dr. Leach, ‘‘ Head united 
with the thorax,”) isa very distinct part of the body, although when at rest it is thrown 
backwards, its upper surface being brought into contact with the dorsal membrane, and 
its under surface consequently being upwards. It is affixed to the anterior part of the 
dorsum, a short distance behind its front margin, by means of a leathery attachment, 
which, when dried, assumes the appearance of a distinct neck, thus enabling us to ac- 
count for Latreille’s statement of the head of his misnamed Nyct. Blainvillii: being 
“emplanté, au moyen d’un article trés court, servant de pedicule, sur le dos du thorax;”’ 
by this means the head is not only raised perpendicularly, but is also advanced in front 
until it assumes a horizontal direction. The head itself is small, and, as Latreille has 
well described it, in the form of a reversed cone ; but it is crustaceous, and not coria- 
ceous. M. Dufour states that its place of insertion is ‘dans l’échancrure antérieure 
du corselet justement entre les hanches des pattes de devant ;” but in no individual 
which I have examined is the anterior margin of the thorag at all emarginate, being on 
the contrary quite rounded, and the head affixed behind rather than between the fore 
legs. The anterior superior margin of the head is slightly emarginate, but much more 
deeply on the under side, where the large base of the central apparatus of the mouth 
is attached. The upper margin (forming the base of the reversed cone) is furnished 
with sete, the remainder of the head being smooth and depressed. 
202 
