ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 573 



which has now been obtained from the branchial cavity of Pachygrapsus 

 transversus. The young female is described and figured for the first 

 time. The contrast between the narrow elongate male and the oblong 

 oval adult female is striking. 



New Amphipod from Costa Rica.*— T. R. R. Stebbing describes a 

 new Talitrid species, Orchestoidea biolleyi sp. n. The genus Orchestoidea 

 Nicolet agrees with both sexes of Talitrus and with the female of Talor- 

 chestia in having the first gnathopod simple, differing from the male of 

 Talorchestia and both sexes of Orchestia, in which the first gnathopod is 

 subchelate. 



Spongicolous Crustaceans.f — J. F. McClendon has studied at Tor- 

 tugas Synalpheus Isevimanus longicarpus Herrick, which lives in great 

 abundance in the cavities of the loggerhead sponge. In the sponge there 

 are also some Amphipods, which go deeper, and undetermined Potoniids 

 which resemble the Alpheids in size and shape and have very similar 

 habits. Whereas Alpltseus has the first pan' of thoracic legs greatly and 

 asymmetrically developed, the same is true of the second pair of thoracic 

 legs in the Potoniid. In both animals the largest claw can be closed 

 with such rapidity and force as to produce a loud snapping sound. It 

 is probable that the large claw is for defence, and that the animal feeds 

 on the sponge or on the food swept in. The resemblance between the 

 Alpheids and the Potoniids is probably rather one of convergence than 

 of protective mimicry. 



Sacculina on Shore-crab.J — F. A. Potts points out that while 

 Oxyrhyncha are sterilised completely by Sacculina, the common shore- 

 crab {Carcinus msenas) when attacked by the same parasite offers a case 

 of slight or incipient modification. Details are given of the change in 

 the abdomen of the male, which becomes broader (more female-like) and 

 has the lost jointing between the third, fourth, and fifth segments 

 re-established. There was no diminution in size of the copulatory styles 

 and no appearance of the abdominal swimmerets which are charac- 

 teristic of the female. In the female no change was ever detected in 

 the abdomen as the result of parasitism. The effect on the gonads is 

 slight — the most noticeable change being the failure of the female to 

 produce large heavily-yolked eggs. The testes continue to produce 

 spermatozoa and the ducts are filled with spermatophores. The case of 

 Carcinus may be compared with that of the " stylopised " males of bees 

 (Andrena) which undergo considerable external change, but the testis of 

 one side remains fully developed and functional. The prevention of 

 moulting is regarded as due to a mechanical disability, the Sacculina 

 acting as a rivet and preventing the fleshy part of the abdomen from 

 beino- withdrawn from its chitinons base. 



'B 



Alimentary Canal and Food of CopepodaJ — W. J. Dakin has 

 studied a number of common marine Copepods. He finds that the 



* Proc. U.S. Nat. Museum, xxxiv. (1098) pp. 2-41-4 (1 pi. and 2 figs.). 

 + Carnegie Inst. Washington, Y'earbook No. 7 (1908) p. 128. 

 X Proc. Cambridge Phil. Soc., xv. (1909) pp. 96-100 (2 figs.). 

 § Internat. Rev. Hydrobiolog., i. (1908) pp. 772-82. 



