446 THE VOYAGE OF H.M.S. CHALLENGER. 



formed, as all those which were seen in the second chamber consisted only of a central 

 core and a layer of male cells, while those which were contained in the thick-walled 

 third chamber had an outer enveloping capsule. 



" I have found several specimens with a fully-developed spermatophore on one side 

 of the body and none on the other side, and was thus enabled to thoroughly satisfy 

 myself of the presence of two vasa deferentia, and two external openings. 



" I was unable to discover how the spermatophore is transported to the body of the 

 female, or what part the clasping organ upon the first pleopod of the male performs 

 during the act of copulation. 



" Upon several occcasions I observed a male clinging to the basal joints of the first 

 antennas of a female, but as I never succeeded in getting the pair under a lens without 

 separating them, I made no careful examination. Copulation usually takes place during 

 the daytime, or at least this was the case in every instance which I observed. In several 

 cases I found female specimens with a simple fresh spermatophore attached to the opening 

 of the seminal receptacle. This opening is situated between and a little anterior to the 

 basal joints of the third pair of thoracic limbs. As the spermatophore gradually dis- 

 charged its contents, it was easy to see that both the central core and the investing 

 layer of spermatozoa escaped from the outer sheath and passed into the seminal receptacle. 

 In all the breeding females which I have observed the spermatozoa filled the posterior, 

 and the transparent core of the spermatopkore the anterior half of the spermatic receptacle. 

 The ovary is very long, and it lies under the intestine, reaching from the fifth abdominal 

 (pleonic) somite to the posterior edge of the carapace, where it bends upon itself at right 

 angles and runs clown to its external opening, which is upon or close to the median line 

 of the ventral surface, a little in front of the third pair of pereiopods. The wall of the 

 ovary is so very thin and delicate that I was not able to detect it at all except when it 

 is filled with ripe ova. These are very much elongated, granular, and slightly opaque ; 

 and there does not seem to be any shell around them. They are very elastic, and undergo 

 great changes of shape as they pass through the small oviduct. 



" Oviposition occurs between 9 and 10 o'clock in the evening, and occupies only 

 a few minutes. 



" After the eggs are laid they are spherical, transparent, and each one has a rather 

 thick shell. They are attached, in a loose bunch of twenty or more, to the last pair of 

 thoracic limbs, and in order to save space I have shown them in fig. 74, although the 

 specimen from which the figure was drawn had not laid any of its eggs. 



" As I obtained very few ripe females, I was not able to sacrifice one of them to study 

 the reproductive organs under pressure, and I am therefore unable to decide whether any 

 parts of this system are double; but I feel confident that there is only one spermatic 

 receptacle, and the opening of the oviduct seems to be upon the median line." I have 

 been induced to quote Professor Brooks' memoir on this subject very fully because of its 



