ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 643 



He proposes to inquire whether the blood of the skate, which is also 

 ■electric, is equally toxic, and whether the blood of non-electric Selachians 

 has or has not the same property. 



Mitsukurina Owstoni.* — Leon Vaillant describes a specimen of this 

 deep-sea shark, the first to reach Europe, and the third obtained. It 

 was named in 190o by Jordan from a specimen in the museum at 

 Tokyo. The present specimen is 2 * 5 metres in length. Vaillant gives 

 •descriptive notes on the vertebral column and skull, and finds that the 

 animal belongs to the Lamnidte, with affinities linking it to Oxyrhina, 

 Lamna, and Odontuspis. 



Parasites of Fishes.f — A. Scott gives a list of parasites from fishes 

 •caught in the Irish Sea. Of Protozoa there are four species : — from 

 Phuronectes flesus, a sporozoon, Lymphocystis johnstonei ; from the 

 plaice a species of Glugm and Sphccrospora platessce ; and Glugea lophii 

 from Lophius. The occurrence of ten species of Trematodes and forty- 

 six species of Copepods is noted. 



Plankton of Wisconsin Lakes.} — C. D. Marsh has made a com- 

 parative study of the plankton of Winnebago, Green, and other lakes. 

 The author discusses the distribution of Cyclops brevispinosus and C.pul- 

 chellus ; the "bloom"; the annual distribution of the total plankton; 

 constituents which produce plankton maxima ; amount in different years ; 

 and, comparatively, the plankton of the different lakes. On comparing 

 the plankton of successive years, it is apparent that the balance of life is 

 maintained much more evenly in deep lakes than in shallow. In the 

 shallow lakes there is always an over-production of plants in the summer 

 as compared with the animals. This is so much the case that sometimes 

 in midsummer the water through the decay of the plants may become 

 actually poisonous to the fish. From the point of view of fish produc- 

 tion the shallow lakes must be considered the more valuable. Under 

 similar favourable conditions deep lakes are never so productive as the 

 shallower ; yet the author thinks the difference has been greatly ex- 

 aggerated. 



INVERTEBRATA. 



Mollusca. 

 y. Gastropoda. 



Anatomy and Affinities of the, Trochidse.§ — W. B. Randies reviews 

 the structure of a number of species of Trochus. His investigations 

 have revealed such a striking similarity of structure as to necessitate the 

 reduction of sub-genera amongst British Trochidse. The section Trocho- 

 oochlea cannot be retained, T. /meatus and T. turbinatus being referable 

 to the division Gibbula. There is a very great similarity in the digestive, 

 excretory, circulatory, and nervous systems of Trochidge and Pleuroto- 

 maria. The author confirms Pelseneer's view that a right reno-pericardial 

 oanal exists in the Trochidae, and considers that the kidney of the Mono- 



* Comptes Rendus, cxxxviii. (1904) pp. 1517-8. 



t Rep. Lancashire Sea Fisheries Lab., 1904, pp. 33-45. 



\ Bull. Wiscon. Geol. and Nat. Hist. Survey, xii. (1903) Sci. Ser. No. 3, pp. 1-94. 



§ Quart. Journ. Micr. Sci., xlviii. (1904) pp. 33-78 (3 pis.). 



