Miscellaneous. 411 



The white substance of the Crayfish secretes in a manner 

 analogous to that of the bladder ; its cells are similarly swollen at 

 their extremity into large clear vesicles, distinct from the body of 

 the cell. As regards the cortical substance of the Crayfish, and the 

 labyrinth of the other Crustacea, several vesicles exist at once in 

 the same ceU : they are, in general, tolerably numerous, oblong, 

 and ranged regularly side by side : they then present the appear- 

 ance of a sort of palisade, covering the cells, and the elements of 

 which correspond pretty exactly to the striation of the bodies of 

 the cells. The saccule equally secretes, by separating cellular por- 

 tions, which are expelled in the shape of vesicles frequently coloured 

 yellow. — Comptes Bendus, tome cxiii. no. 4 (July 27, 1891), 

 pp. 223-225. 



On the Circulatory and Respiratory Apparatus of certain 

 Arthropods. By M. A. Schneider. 



Amphipods. — I have injected Talitrus, the ordinary fresh-water 

 Shrimp, and Nij^hargus, In all I found that the heart emits three 

 pairs of lateral arteries, of which the first two arise immediately 

 below the second and third pairs of cardiac ostia, while the third is 

 given off pretty nearly in the middle of the space which separates 

 the third pair of cardiac ostia from the origin of the posterior aorta. 

 These lateral arteries give rise to numerous ramifications, which 

 principally pass to the biliary apparatus. 



Claus described lateral arteries in the Hyperina : to-day we are 

 able to affirm that they exist in the whole group. 



Arachnida. Scorpion. — The vessels formerly described by New- 

 port and Blanchard in the Scorpion have more recently been 

 regarded as simple lacunae. Their primitive value must, however, 

 be retained for them. 



Sections of these vessels, in particular of the spinal artery, show 

 a distinct wall, with striated muscular fibres, which are absent, on 

 the contrary, in the neurilemma ; successful injections never show 

 extravasations, and those which contain nitrate of silver everywhere 

 disclose a splendid endothelium. The same results are obtained in 

 the Araneida. 



The vascular topography, as determined by my predecessors, is 

 correct in its ensemble ; but many new details have presented 

 themselves to me, into a detailed description of which I shall not 

 enter, but confine myself to mentioning: — (1) Five transverse 

 anastomoses between the two halves of the annular vessel, each 

 giving off a sternal artery, which plunges into the sub-oesophageal 

 mass ; (2) four other sternal arteries, which arise below the initial 

 portion of the spinal artery, and of which the posterior becomes the 

 artery of the pectines ; (3) anastomoses in the caudal region, or 

 post-abdomen, not such as Newport described, but between the two 

 branches formed by the bifurcation of the sternal arteries of this 

 region and the posterior aorta. 



Akaneida. — I have studied the lung of Spiders and am abso- 

 lutely convinced that the chitinous envelope, recently described as 



