626 C4E0FFRET S]\I1TH. 



NeapoHtan races of Sacculina wliicli iufest luaclius inauri- 

 tanicus' (Lucas) aud Pacliygrapsus luarnioratus 

 (Fabr.), I did not succeed iu keeping tliem alive for more 

 than four days^ or in observing the transformation into 

 the Cypris stage. 



TheNaupliiof the Sacculina on P. marmoratus appeared 

 to be hardier than those of the parasites on I. mauri- 

 tanicus, and I suggested (2^ p. 44) that this might be due 

 to the former crab being a distinctively littoral species, and 

 tlius subjected to more varying conditions than the Spider- 

 crabs ; this suggestion is probably correct since the Nauplii 

 of the Sacculina of Carcinus mtenas are evidently the 

 hardiest of all, and this crab is more decidedly littoral in 

 habit than P, marmoratus. 



The successful rearing of the Nauplii of Sacculina 

 carcini was effected by selecting "purple" Sacculinas aud 

 obtaining a batch of healthy Nauplii; tbey Avere then trans- 

 ferred to sea water which had been purified by mixing with 

 powdered charcoal and filtering in the manner used by the 

 Director of the Plymouth Laboratory, Dr. E. J. Allen, in his 

 preparations of pure cultures. 



It is of extreme importance that water of great purity 

 should be used, since the larvjB are to live in this water for 

 nearly a fortnight, and the multiplication of Infusoria and 

 Algfe iu the water is highly injurious to them. The larvte, of 

 course, require no food, since they possess no gut and subsist 

 entirely on the yolk reserves which they contain. 



The Nauplii, actively swimming the whole time, undergo 

 four successive moults iu four days ; they are then transformed 

 by a single moult into the Cypris larva). Before these larva) 

 fix upon their host, Delage observed that they had to spend 

 at least two more days in a free-swimming state ; fixation 

 also only takes place in the dark. These two points I am 

 able to confirm from my own observations. 



The fixation of the Cypris larva?, as followed by myself, 



' By an error in nomenclature I. mauritanicus (Lucas) was called I. 

 Scorpio (Fabr.) flirougliout in my monograph (2). 



