ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 351 



the spermatozoa come in contact with the ova under normal conditions, 

 the capsule is usually applied to the shell of the egg- and the nuclear 

 cup is directed away from the egg. In this position e version takes 

 place and the ejected central body, the inner tubule and the capsule 

 with its contents are turned through the shell into the egg. The 

 nuclear cup is left on the outside and soon falls off. The wall of the 

 capsule, together with its everted contents, which forms the sperm-vesicle, 

 sinks into the cystoplasm of the ovum, where it is enlarged and trans- 

 formed into the male pronucleus. The substance within the capsule 

 may be derived from the nucleus of the spermatid and is probably oxy- 

 chromatin which deposits basichromatin after it enters the egg, and so 

 gives rise to the chromosomes in the male pronucleus. 



Development of Caridea.* — E. Sollaud notes that in most Carideathe 

 ova are small, the larva is a nauplius, and in subsequent development 

 the uropods appear before the pleopods. In many species, however, the 

 ova are large and rich in yolk, the larva emerges at an advanced stage, 

 and the uropods appear after the pleopods. The author argues that the 

 early appearance of the uropods in the forms with small ova is not an 

 hereditarily fixed character, but is conditioned by an actual factor in 

 larval life— the incessant movements of thetelson in the very active free- 

 swimming larva. 



Thompsonia.t — F. A. Potts discusses this little-known Rhizoce- 

 phalian, first noted by Kossmann in 1874 as a parasite upon the small 

 crab Melia tesselata, from the Philippines. Superficially, the parasite 

 consists of a number of small external sacs, sometimes 200 on one host, 

 which spring from the limbs of the host. Unlike Coutiere and Hafele, 

 who regarded each sac as a separate individual, Potts maintains that 

 they are budded off from one root system. The external sacs are 

 probably homologous with the visceral mass of the typical Rhizoce- 

 phalian. It seems, then, that nerve-ganglion, reproductive ducts, and 

 muscular tissue have been lost, and probably the testis as well. Only 

 the ovary is left, and reproduction appears to be parthenogenetic. The 

 larvae develop in the sacs and are liberated by a moult. 



By observations on infected specimens of a species of Synalphens, 

 Potts has shown that after the moulting of the host another crop of 

 sacs are produced by the root system. 



It seems probable that Thompsonia is not primitive but highly 

 specialized. The external sacs are little more than ovaries placed ex- 

 ternally to allow of the escape of the larvas. The adoption of partheno- 

 genesis, as in Sylon and Mycetomorpha, has made it possible to dispense 

 with testes and gonadial ducts. In may be that in Peltoyaster socialis 

 the hundred or more sacs are not due to a simultaneous fixation of 

 gregarious larvae, but to internal budding, as in Thompsonia. 



New Parasitic Copepod.* — R. Dollfus describes Trochicola en- 

 terica g. et sp. n., the female of which occurs in the rectum of Zizyphinas 



* Comptes Rendus, clviii. (1914) pp. 971-3. 



t Proc. Cambridge Phil. Soc, xvii. (1914) pp. 453-9 (2 figs.). 



J Comptes Rendus, clviii. (1914) pp. 1528-31. 



