413 



June and July; cleavage regular and nearly equal, with the formation 

 of free-swimming, ciliated blastulae which develop into ciliated em- 

 bryos provided with ventrally-placed mouth , a pair of ocelli , and an 

 anterior and a posterior flagellum, or tuft of much longer, consolidated 

 cilia. The embryos leave the egg-membrane in this condition, and 

 usually remain in the mucous tube or among the egg-masses of the 

 host, but may swim freely in the water. The larval integument, with 

 its cilia and flagella, is apparently shed, as described by vanBeneden 

 and Dieck (loc. cit.). At this time the embryos assume the form of the 

 adult, and crawl about instead of swimming. The integument of the 

 young worms now becomes covered with cilia as in the adult. After 

 remaining for a time among the egg-masses of the host, or perhaps 

 until the eggs have hatched, they wander about on her body, eventu- 

 ally reaching the gills. They are found in this position in July or 

 August and later, and here they probably remain until the crab pro- 

 duces another batch of eggs the following season. At this time they 

 migrate again to the egg-masses where they become sexually mature. 

 Those embryos which swim away and which do not chance to find 

 another suitable crab probably perish. The observations of the Euro- 

 pean observers mentioned are mainly in accord with the account as 

 here given. As observed both by Mcintosh and Dieck (loc. cit.), ferti- 

 lization and early cleavage sometimes takes place within the body of 

 the parent. 



Carcinonemertes epialii Coe. 

 American Naturalist, Vol. XXXVI figs. 1 — 9, 1902. 



A very much smaller and less slender species than C. carcinopJiila, 

 being only 4 — 6 mm in length, when sexually mature; posterior 

 chamber of proboscis (figs. I, 2 pc.) much more swollen than in 

 Koelliker's species. Stylet a little les sthan half as long as basis, 

 which is but slightly larger posteriorly than at attachment of stylet. 

 Other anatomical peculiarities are noted in the paper cited. In general 

 appearance, color, arrangement of ocelli, oesophagus, intestine and 

 brain, the two species are very similar. 



Upwards of 100 sexually mature individuals, about 4 — 6 mm in 

 length and less than 0,5 mm in diameter, were collected from the egg- 

 masses of a single crab [Epialtus product us) at Montery, California. 



The only other nemertean known to be parisitic on crabs is the 

 form which has been found on Nautilograpsus minutus in the region 

 of the Sargasso Sea, and which was referred by Willemoes-Suhm> to 



1 Ann. Mag. Nat. Hist. Vol. XIII. p. 411. PI. XVII fig. 4. 1874. 



