ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 555 



New Rhizocephalid Type.* — H. Coutiere found under the abdomen 

 ■of three species of Alpheus a new Rhizocephalid parasite, remarkahle 

 in being gregarious. A hundred or more occurred together, forming a 

 mass like a bunch of eggs. The new form, for which the name Thyla- 

 ^oplethus is proposed, approaches Thompsonia globosa Kossmann. It 

 seems certain that the larvae fasten themselves directly on the place 

 where the adults are found. 



Structure of Thylacoplethus.f — H. Coutiere describes some of the 

 remarkable features in the internal structure of this new Rhizo- 

 cephalous parasite which infests species of Alpheus, — T. haddoni on 

 A. avarus, T. edwardsi on A. edwardsi, and T. heurteli on A. macrochirus. 

 In its mode of fixation, in its simple structure, in its gregarious cha- 

 racter, the genus Thylaeoplethus may be taken as representing a very 

 primitive type, one of the first essays in parasitism on the part of these 

 Crustaceans. 



Scottish Crustacea. t — T. Scott describes the Is<pod Pleurocrypta 

 longibrancMata obtained on a species of Qalathea from the Clyde, and 

 PI. patiencei sp. n. from a specimen of Caridion gordoni. The new form 

 is called after Alexander Patience who has done much good work in 

 collecting Clyde Crustaceans and who sent the author a new Bopyrid, 

 Pleurocrypta cluthse sp. n. The communication includes a note on Try- 

 phana malmii Boeck, a somewhat rare Amphipod obtained on the deep 

 water about nine or ten miles off Aberdeen. 



Commensal Schizopod.§ — J. Bonnier and C. Perez describe Gnatho- 

 mysis gerlachei g. et sp. n., type of a new family of Schizopods, found at 

 Massaouah on the Red Sea. It is perhaps more remarkable in habit than 

 in structure, for it occurred (four specimens) within the topmos-t turn of 

 the spire of gastropod shells inhabited by Pagurus brevipes. 



Early Development of Lepas |j — M. A. Bigelow discusses the matu- 

 ration v fertilisation, cleavage, and germ-layer formation. His research 

 is mainly a study in cell-lineage on to the 62 -cell stage. 



Lepas resembles most other Crustacea (a) in respect to the position 

 of the blastopore, which is ventral and posterior ; (b) in the extension of 

 the entoblast and mesoblast from the blastopore as a starting-point ; 

 and (c) in the mode of formation of the organs of the larva. 



In Lepas, as in most other Crustacea, the mesoblast and entoblast 

 originate in the region of the blastopore from cells which, speaking in 

 general terms, at first lie in the blastoderm and later migrate into the 

 cleavage-cavity. 



Among the migrating mes-entoblastic cells one can distinguish in 

 Lepas the individual cells of the entoblast and of two varieties of meso- 

 blast. Representatives, if not precise homologues, of these kinds of 

 cells are probably present both in other Entomostraca and in the higher 

 Crustacea. 



The origin, relative position, and fate of all the cells of all the cleav- 



* Comptes Rendus, exxxiv. (1902) pp. 913-5. f Tom. cit., pp. 1452-3. 



% Ann. Nat. Hist., x. (1902) pp. 1-5 (1 pi.). 



§ Comptes Rendus, exxxiv. (1902) pp. 117-9. 



|| Bull. Mus. Zool. Harvard, xl. (1902) pp. 01-141 (12 pis.). 



