THE AMERICAN LOBSTER. 
157 
THE OVIDUCT. 
The oviduct is a straight tube of nearly uniform caliber (figs. 119, 123 or?), which 
opens to the exterior in a hairy papilla on the coxopodite of the third pair of pereio- 
pods. The skin is folded in the mouth of the opening so as to form a valve which 
prevents the ingress of water. The appearance of the duct when eggs are passing 
out is shown in fig. 119. The ovary had collapsed, but these eggs failed of passage. 
The structure of the duct is the same throughout. It has a thin wall of muscular 
and connective tissue, and a characteristic epithelium of tall columnar cells. The 
latter undergo so marked a change at the period of ovulation that there can be little 
doubt that they have some important function to perform. As shown by a comparison 
of tigs. 167, 168, taken respectively from a lobster just before and just after ovulation, 
these cells become very greatly elongated and vesicular. One would infer that they 
secrete a liquid which is poured out with the eggs when they are laid. Whether these 
cells take any share or not in forming the cement I do not know. 
THE SEMINAL RECEPTACLE. 
The sternal pouch of the female was noticed and roughly figured by Nicholls in 
the Philosophical Transactions of the Royal Society for 1731, but he entertained a 
wrong notion of its function. His interesting and unique account of this organ is as 
follows ( 141 ): 
Between the two last legs and the two legs above them there are two processes, which, from their 
resembling the nymph* of women, I shall term nymph*form processes. These processes are covered 
with hair, and unite at their bases without leaving any passage. * * * The two processes, which 
I have termed nymplneform, in the female make a more obtuse angle at the union of their bases, are 
less hairy, and leave a passage, through which it is probable the ova are emitted, to be affixed to the 
appendages under the tail. 
This remarkable conclusion reached in the last paragraph is unexplained even by 
the forced comparisons which were employed. 
The observation of Nicholls was forgotten, and the structure which he imper- 
fectly described was overlooked until its true function was discovered by Bum pus 
in 1891 ( 30 ). 
The seminal receptacle lies on the under side of the female near the junction of 
the thorax Avith the abdomen. (For its position and general appearance see plate 7, in 
which the median slit is clearly shown, and for details, fig. 130, plate 38.) Its paired 
wing-like processes, the enlarged sterna of the seventh thoracic segment, are tinged 
with bright blue and form, with a wedge-like middle piece belonging to the sternum 
of the eighth thoracic segment, a somewhat heart-shaped body. There is a median 
slit with elastic edges, and if these are depressed, as Bumpus remarks, a grayish 
substance, the spermatic fluid, sometimes oozes out. The middle sternal piece is 
prolonged inside the chamber into a stout keel-shaped body strengthened with thick 
deposits of chitin, which have a yellowish color and horny consistency. This is sup- 
ported by a pair of irregular rods belonging to the endophvagmal system, which meet 
on the middle line. If the molted shell of a lobster is examined, in place of a solid, 
horny keel, a membranous pouch is found. The solid keel-shaped mass is probably 
absorbed before a new keel is formed. In the living animal the seminal receptacle is 
a narrow, irregular cavity. 
