ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 27 



of nomenclature. Full diagnoses of the types referred to are given. 

 Delavalia mimka T. Scott becomes Beatriedla mimica g. n. Delavalia 

 giesbrechti var. T. Scott, 1899, becomes D. normani T. Scott, n. n. 

 Jonesiella hycencc T. Scott, 1893, becomes Thompsonula hyamce, J. C. 

 Thompson. . 



Seasonal Dimorphism in Daphnids.* — W. Ostwald has shown in 

 detail that structural changes as well as functional changes in Daphnids 

 are correlated with changes of temperature. Increased temperature 

 almost always increases the fertility, the rate of reaching reproductive 

 maturity, and so on, but it also affects the form of the head, especially 

 at a critical period at the beginning of the second stage in the 

 development. 



Ephippium of Daphnia hyalina.f — Adolf Zwack gives a detailed 

 account of the fully-formed ephippium, its outer wall of elongated 

 hexagonal prisms, its inner lining which consists of a simple lamella with 

 a peculiar structure. He discusses the development of the ephippium, 

 the sudden filling with air, and the final separation. 



Annulata. 



Spermatogenesis of Earthworm.:}: — E. Bugnion and N. Popoff 

 describe the spermatogenesis of Lumbrieus agricola. There are four 

 phases : (1) A phase of proliferation, starting with the primitive germ- 

 cell, leads to the formation of the follicle. It occurs in the testes ; it 

 gives rise to syncytial groups of 2, 4, 8, 16 elements, and then to 

 colonies of follicles of 32, 64, 128, or more cells, united by short stalks 

 directed towards the centre. (2) A phase of dissociation involves a 

 division of the follicle into groups of spermatogonia, pyriform cells 

 with delicate stalks directed towards the centre. (3) A second phase 

 of proliferation (segmentation) may raise the number in a stalked group 

 from 2, 4, or 8, to 16 or 32. (4) A final phase of multiplication trans- 

 forms a group of 32 into a morula of 64 spermatocytes round a central 

 blastophore, and finally leads to the finished morula which has normally 

 128 spermatids. 



Indian Species of Chaetogaster.§ — Nelson Annandale describes 

 Ohwtogaster bengalensis sp. n., the first recorded Asiatic species. The 

 prostomium forms a large sub-circular sucker ; there is a smaller sucker 

 at the posterior end ; the oesophagus is longer than the pharynx ; there 

 is a sense-organ (otocyst ?) in the brain ; in the first few segments the 

 two ventral nerve cords are separate ; the first pair of nephridia is 

 larger than the others ; the setae occur in bundles of 15-17 on each 

 side of the ventral surface ; the body is colourless and almost trans- 

 parent, about 10 mm. in length, with about 20 segments. 



The animal usually clings to a water-snail ; the locomotion is mainly 

 by the suckers : the anterior setaj help in seizing the prey (small crus- 



* Arch. Entw., xviii. (1904) pp. 415-51 (7 figs.). 



f Zeitschr. wiss. Zool., lxxix. (1905) pp. 548-73 (2 pis.). 



X Arch. Zool. Exper., xxxiii. (1905) pp. 338-89 (4 pis.). 



§ Journ. and Proc. Asiatic Soc. Bengal, i. (1905) pp. 117-20 (1 pi. and 1 fig.). 



