228 SMITHSONIAN MISCELLANEOUS COLLECTIONS [voL. 48 
thick epithelial layer which seems to be exactly like the spermato- 
phoral cell layer of normal males. I therefore have little doubt that 
this specimen was capable of producing some spermatozoa. From 
the appearance of the ovaries it seems very probable that had the 
specimen been allowed to live, it would have produced a large 
number of perfectly normal eggs. 
It might be added that during the time the specimen was kept 
alive it was seen in conjugation with a female of the same species 
and a little later was itself seized and held for a short time in 
the usual manner by a male. The latter, however, is a matter of 
little importance as I have several times observed the same thing 
in the case of two males neither of which was hermaphroditic. 
It will be observed that of all the specimens belonging to the 
genus Cambarus described both by Dr. Faxon and myself only a 
single one, the individual of C. affinis, had perfectly developed 
external male characters. In all the other cases, with the possible 
exception of specimen number I of C. spinosus, the female char- 
acters were so strongly developed ‘as to be unmistakable indices to 
the sex. Such dissection as was possible under the circumstances 
bore out perfectly the external indications and we may say without 
hesitation that the individuals were females. Even in the case 
of the specimen of C. affinis the internal organs pointed unmis- 
takably to the conclusion that it too was functionally more a 
female than a male. It would therefore appear that in the genus 
Cambarus at least, hermaphroditic individuals are females which, 
owing to some ambiguity of the formative cells in the embryo, have 
developed to a greater or less degree the characters of the opposite 
sex. The condition is a very rare one and is usually shown in the 
external organs only. It has been observed by students of tera- 
tology that hermaphroditic individuals, in certain species, at least, 
as they grow older show masculine characters more and more 
strongly and it may be that something of the kind occurs in cray- 
fishes. Most of the specimens of these animals which have been 
examined were small, the only fully adult one (C. affinis) had the 
most perfectly developed hermaphroditic characters and the infer- 
ence is possible that this perfection of the male organs had been 
acquired with age. 
In the genus Astacus indications of hemaphroditism appear to 
be quite as uncommon as in Cambarus. Among the Parastacidz 
the condition of apparent hermaphroditism seems to be established 
in the genus Parastacus and may also be found to obtain in Cheraps 
but evidently is rare or altogether wanting in the other genera. 
