MR. J. O. WESTWOOD ON NYCTERIBIA. 285 
and rounded. Montagu, however, who describes the abdomen of the styliferous spe- 
cimens of the species from which Dr. Leach derived his characters as being apparently 
composed of three divisions, states that in another specimen the abdomen appeared four- 
jointed, more ovate, tumid, and destitute of posterior appendages ; this he regarded as 
a female, and the former as a male. From my subsequent observations it will be seen 
that the supposition of Dr. Leach was the correct one. Latreille also differs in opinion 
from Dr. Leach, considering the styliferous individuals as males, and those with a 
greater number of articulations, and without exserted terminal appendages, as females ; 
and he consequently describes the abdomen of the supposed female of his misnamed 
Nyct. Blainvillii as ovoid, six-jointed, the last joint being elongate-conic, narrowed to 
the tip, and truncate ; but as he has not mentioned the existence or nonexistence of 
inflected styles or other male apparatus, a slight degree of doubt must remain as to 
the sex of his insect, notwithstanding that its six-jointed abdomen would induce us to 
suppose, with reference to the characters of Colonel Sykes’s insect, that it must be a 
male; as, indeed, M. Dufour has presumed. 
The last-named author ! has described the abdomen of two kinds of individuals of his 
Nyctéribie de la Chauve-Souris, that of the female being cylindric-oval, apparently 
destitute of articulations, furnished on its upper surface with three pairs of pectiniform 
series of short hairs varying in their direction, and setose at its extremity: that of 
the male is smaller, oblong, and exhibits on the upper side six distinct segments, of 
which the last is slightly attenuated and truncate at the tip. He adds, “‘ L’exploration 
la plus attentive de l’extrémité de l’'abdomen ne m’a fait découvrir a celle-ci aucun 
appendice, aucun stylet, aucune soie particuliére.”’ He regrets, however, that he did 
not endeavour, by compression, to discover if these organs were not retracted. That 
the former of these descriptions is taken from a female insect is not to be doubted ; and 
the other description is so different as to induce us to believe that it is taken from a 
male, notwithstanding the want of any visible male organs: these, however, as we shall 
subsequently see, are occasionally not prominent, but laid closely along the under sur- 
face of the abdomen. And Iamso confident that this would be the case in the real males 
of M. Dufour’s insect, that, should this author be perfectly correct in his descriptions, 
and not have overlooked the male organs, I should feel no hesitation in regarding his 
smaller insects, not as males having the masculine organs retractile within the last seg- 
ment of the abdomen, (which I have never found to be the case,) but as females of the 
same or even of a different species, and most probably in an unimpregnated state ; con- 
ceiving that gestation and subsequent parturition would materially alter the character 
of this part of the body. 
' It should be observed that this author has misstated Dr. Leach’s opinion in his observation, “ Suivant 
M. Leach ce sont les individus qui ont moins de segmens a l’abdomen qui sont les miles.” He has evidently 
mistaken Latreille’s conclusions upon this point, in the ‘ Dictionnaire d’Histoire Naturelle,’ for the opinion of 
Dr. Leach. 
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