ZOOLOGY AND BOTANY^ MICROSCOPY, ETC, 507 



vessel of considerable size. He finds, at the origin of all the arteries 

 which arise from the heart or the dorsal vessel, a pair of pocket-valves, 

 which agree in structure with those found in the Phyllopoda and the 

 Hedriophthalmata. A sympathetic nerve accompanies the dorsal 

 vessel, and seems to correspond to the sympathetic of the heart of the 

 Hyperida. The absence of antennary glands would appear to be 

 compensated for by the presence of glands connected with the 

 rectum. 



Copepoda living in Molluscs and Ascidians.* — C. W. S. Auri- 

 villius has investigated the Copepoda inhabiting molluscs and Ascidians 

 on the Swedish coast, and publishes the results in two papers 

 illustrated with seven double plates. Only two species, both belong- 

 ing to the Sapphirinidae, were found inhabiting molluscs, a species 

 of Lichomolgus on species of Doris, and a new genus and species 

 (Modiolicola insignis) upon the branchiae of Modiola and Mytilus. 

 Twenty-one species, representing seven genera and five families, were 

 found in the branchial sacs of Ascidians, two new species being added 

 to those already described by Thorell and others. Nearly all the old 

 species are redescribed, and a large part of them figured, and ana- 

 lytical tables of the genera and species given. 



American Parasitic Copepoda.f — Prof. E. Eamsay Wright gives 

 an account of some Copepods parasitic on fresh- water fishes ; the first 

 of these is Ergasilus centrarcMclarum n. sp., which was found on the 

 gills of various CentrarcJiidce ; in giving the details of this form an 

 opportunity is taken for expressing the opinion that, when a revision 

 of the species of Ergasilus is undertaken, it will probably be found 

 that the form of the appendages offers valuable specific characters. 

 In dealing with Achtheres micropteri n. sp., there are some notes on 

 the spermatophores. 



Vermes. 



Development of Annelids.t — W. Salensky describes in detail the 

 development of Nereis cultrifera, the eggs of which are laid in large 

 lobate gelatinous masses, and each has in addition to the gelatinous 

 covering a delicate vitelline membrane, which, as in all other Annelids, 

 is finally converted into the cuticular membrane of the larva. The 

 author does not agree with Goette in giving to the micromeres the 

 name of ectodermic, or to the macromeres that of endodermic cells ; 

 for the ectoderm is not only formed by the micromeres, but also at the 

 expense of the larger cells. The cells do not definitely acquire their 

 laminar significance until after the completion of the epiboly and the 

 development of the ectoderm. The share in the macromeres is taken 

 not only by the marginal, but also by the median portion of the 

 ectoderm. Forty-eight hours after deposition epiboly has advanced 

 so far that the macromeres, which are always four in number, are com- 

 pletely enveloped by the ectodermal cells ; these last are not equally 



* Ofvers. K. Svenska Vet. Akad. Forh., 1882, Nos. 3 and S. 

 t Proc. Canad. lust., i. (1883) pp. 243-54 (2 pis.). 

 J Arch. Biol., iii. (1882) pp. 561-604 (3 pis.). 



