ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 575 



actual formation of these coagula in situ at a wound may be watched in 

 the Amphipod Gammarus, and the part which they play in the natural 

 arrest of haemorrhage thus studied. They help to stop the bleeding by 

 forming an adherent bunch of globules or botryoidal mass at the site of 

 injury. To these globules issuing blood-cells tend to adhere, thus 

 further clogging up the paths by which the blood escapes. The birth 

 of one of these globules is accompanied by a considerable output of 

 kinetic energy, the explosion consisting not merely in a shedding out of 

 material from the corpuscle, but in an actual rending and breaking 

 apart of the immediately surrounding clot. This process suggests an 

 analogy with MacDonald's hypothesis regarding the cause of muscle 

 contraction. The part played by these localized coagula must not be 

 taken in the meantime to supersede or dispose of the cell-agglutination 

 hypothesis put forward by other authors as the cause of the first coagula- 

 tion in Crustacean blood. According to the view here taken, the 

 phenomenon exists alongside of and intimately associated with cell- 

 agglutination as a contributing factor in arrest of haemorrhage. A 

 second coagulation of Isopod blood, this time involving the whole 

 plasma indiscriminately, may be made out in addition to the afore- 

 mentioned localized coagulation. There is no histological evidence to 

 associate this second coagulation with the disintegration of any one 

 particular element of the blood more than another. 



Antarctic Schizopods and Cumacea.* — H. J. Hansen describes 

 from the collection made by the ' Belgica,' Euphausia longirostris sp. n. 

 and E. superba Dana. The latter seems to live everywhere in the 

 Antarctic Ocean, and has been taken by every expedition touching any 

 part of these seas. It is the chief food of seals, e.g. Lobodon carcinophaga. 

 Hansen describes a number of larval forms, and points out that there is 

 much difference in the development of Euphausia superba, E. pellucida, 

 and another species of the same genus. In the order Mysidacea he 

 describes Pseudomma belgicse and Antarctomysis maxima, which occurred 

 also in the ' Discovery ' collections. Two new species of Cumacea are 

 described, Gyclaspis glacialis and Campylaspis frigida. 



Indian Fresh-water Crabs.f — A. Alcock has made a catalogue of 

 the Potainonidge in the Indian Museum — 43 species and varieties of 

 Potamon, 45 of Paratelphusa, and 3 of Gecarcinucus. The Potamonidaj 

 are typical inhabitants of fresh-water, but a few species flourish in 

 brackish water on the one hand and in damp jungle on the other. They 

 are found in ponds, lakes, streams, rivers, and marshes ; and though 

 they flourish most at low or inconsiderable levels in the tropics, they 

 extend into the warmer temperate regions, and are also quite common 

 at considerable elevations in the torrid zone. The Indian forms show 

 great variety of habitat, and even one and the same species, e.g. Paratel- 

 phusa spinigera, may occur from the swamps of Lower Bengal to an 

 elevation of 2000 ft. The variability seems to be considerable. 



The eggs are comparatively large and not extremely numerous in a 



* Exped. Antarc. Belg., 1908 (received 1910) pp. 1-20 (3 pis.). 

 t Catalogue of Indian Decapod Crustacea. I. Brachyura ; fasc. ii. Potamo- 

 nidce ; pp. 1-135 (14 pis.) 



