ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 171 



externa] coloured cuticle, a layer of lens-like white calcareous bodies, 

 which enclose numerous branched passages containing air. They are 

 auxiliary to " gills," where these are present in terrestrial forms. 



Development of Summer Eggs of Polyphemus.* — Alfred Kiihn 

 gives a full account of the segmentation and gastrulation of Polyphemus 

 pediculus, and a survey of later embryonic stages. He makes a com- 

 parison between the development of Polyphemus and that of other 

 Crustaceans, and discusses the question of the determination of the 

 blastomeres. The development is definitely determinate. Particular 

 blastomeres represent definite primordia, as in Annelids and Molluscs. 

 The first two blastomeres get different kinds of plasma, because the 

 ovum shows polar differentiation and the cleavage plane is inclined to 

 an angle to the main axis. A quantum of substance lying at the vege- 

 tative pole comes into a quadrant which is henceforth marked by a 

 special developmental history. Plasmic differentiation in the primary 

 axis of the egg has a far-reaching influence. 



Crustaceans on Alcyonarians.f — Ch. Gravier describes a small 

 Crustacean that forms galls on Primnoisis formosa and Mopsea gracilis 

 from Antarctic waters. Males and females and young forms were found. 

 The males are smaller, but there is no dimorphism. The systematic 

 position is among Lamippidas, and the name Isidicola antarctira sp. n. is 

 proposed. The differences between the new form and the genera 

 Lamippe and Linaresia are indicated. 



Annulata. 



Structure of Branchiura sowerbyi.J — Fr. Keyl gives an account of 

 this East Indian Oligochaet, which Beddard first found in the Victoria 

 Regia tank in the Royal Botanical Society's garden in Regent's Park. 

 Keyl's specimens were found in a similar situation in Gottingen and 

 Frankfurt. It lives in tubes in the mud, and eats the mud. It is pre- 

 judical to the rooting of young plants. The author describes the 

 nervous system, comparing it with that of other Oligochaets, and shows 

 that in spite of apparent unity the two halves are very distinct and form 

 a rope ladder system. The neurochords are discussed in great detail, 

 and Keyl inclines to the view that they were nervous to begin with, but 

 have undergone degeneration. The gills are diverticula of the epithelium 

 of the body and a portion of the circular musculature. An account is 

 also given of nephridia, gonads, and germ-cells. 



Food of Sipunculids.§— Marcel A. Herubel finds that the intestine 

 of Sipunculus nudus, Phascolosoma vulgare, and P. elongntam contains 

 besides sand and shell fragments almost nothing but Diatoms— of which 

 a list is given. 



* Zool. Jahrb., xxxv. (1913) pp. 243-340 (7 pis. and 14 figs.). 



t Comptes Rendus, clviii. (1914) pp. 354-6. 



X Zeitschr. wiss. Zool., cvii. (1913) pp. 199-308 (3 pis. and 56 figs.). 



§ Bull. Soc. Zocl. France, xxxviii. (1914) pp. 317-18. 



