LAND CRUSTACEANS. 89 



Comparing these structures with the same parts in Paguristes and Eupagurxis^, the 

 following points appear. The testis is more compact in Coenobita than in either of the 

 Pagurid genera. In shape it represents, with its hinder swelling, a more definite form of 

 the type foreshadowed by Eupagurus, which is, in this respect, intermediate between 

 Paguristes and the laud genus. On the other hand, in having one spiral section (instead 

 of two, sundered by a straight tube), as also in the small calibre of this region, Coenobita 

 approaches Paguristes rather than Eupagurus. But in the shortness of the very narrow 

 tube which comes immediately before the spiral, that is which separates the spiral and 

 the conducting tube proper, it again resembles Eupagurus. The male opening is in the 

 usual position on the coxopodite of the fifth leg of each side. The portion of the joint 

 which bears the opening is always more or less prominent and, in some cases {C. rugosus, 

 C. perlatus) is, on the right side of the body, prolonged into a penis-like process. In 

 G. perlatus, however, in which this feature is very marked, bringing about a complete dis- 

 similarity between the openings of the two sides, there is no sign of degeneration in the 

 left testis, and its duct may contain sperm. The first abdominal segment being, in both 

 sexes, unprovided with appendages, there is here no copulatory organ of the type common 

 in other Decapods. 



B. The female organs. The ovaries are a pair of simple cylindrical structures lying 

 in the abdomen one on each side of the median line close above the hind-gut along the 

 middle portion of its course. In C. clypeatus the ovaries are separate. In G. rugosus and 

 G. perlatus they join for a short distance at their hind ends^ The oviduct is a simple 

 tube, arising from the anterior end of the ovary and running straight forwards to its small 

 round opening on the ventral face of the coxopodite of the third leg. 



C. The relative numbers of the sexes seem fairly equal, a collection taken at haphazard 

 giving sometimes a small preponderance of one, sometimes of the other. 



viii. Reproduction. Whether Coenobita have a definite breeding season or not, and, 

 if so, when it occurs are questions that still remain to be settled. Certainly, females with 

 eggs may be taken throughout the summer in Ceylon ^ The copulation is another point 

 deserving further investigation. Very little is known on this subject as regards most 

 Decapods. Paguristes is said to insert a penial process into the vulva of the female'', and 

 possibly the same use is made of the " penis " of G. perlatus. That of C. rugosus is too 

 broad for insertion, but is no doubt of use in placing the sperm in some required position. 

 At the same time the reproductive organs of the left side of the body show every sign 

 of being functional in these, as in the other species of the genus, and the problem is thus 

 complicated by the probability that their sperm is deposited in a different way from that 

 of the right side of the body. 



The eggs are carried in large masses attached to the long hairs on the well-developed 

 limbs on the right side of the second, third and fourth abdominal segments of the female. 

 They are arranged irregularly along the hairs^ and fixed, as in other Decapods, by an 



' Grobben, "Beit. Kennt. Mann. Geschlechtsorg. Deka- found great difficulty in finding females with eggs at that 



poden," Arb. Zool. hist. Wien, i. 2 (1878). season. The same is the case in Ceylon. 



- In Paiiuriis they are said to remain separate. ^ Ortmiinn, Bronn's Thierreich, v. 2, p. 1075. 



^ Mr Stanley Gardiner suggests to me that the south- = In Birgus they are in clumps at intervals along the 



west monsoon is the main breeding season in the Maldives. hair. Borradaile, Willey's " Zool. Results," Ft. v. p. 585 



He was in these islands during the north-east monsoon, and (1900), "On the Young of the Robber Crab." 



G. 



12 



