ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 45 



Development of Protodrilus and Saccocirrus.* — Umberto Pieran- 

 toni describes the early stages of development, and the formation of the 

 larva in these two archiannelids. 



Pelagosphsera aloysii.t — Angelo Senna gives a careful description 

 of this pelagic form, and comes to the conclusion that it is simply a 

 larval stage in the development of Slpunculus. 



Revision of the NaididsB.^ — E. Piguet has studied the Swiss 

 Xaididfe (28 species), and gives a diagnostic key and a systematic 

 revision. The various genera — Paraaais, GImtogaster, Ophidonais, 

 Naidium, Nais, Dero, etc., are passed under review. The influence 

 of the seasons on the manner of life, the coloration, the budding, and 

 the sexual reproduction is illustrated. 



Naididse of North America.§ — L. B. Walton describes the Naids 

 of Cedar Point, Ohio, and gives synoptic tables for the separation of 

 the genera of this family, and similar tables of species for the genera 

 represented. Five genera are dealt with in detail, and seven new 

 species are described. 



Maturation-processes in Ophryotrocha puerilis.]] — A. and K. E. 

 Schreiner describe the processes of maturation in the oogenesis and 

 spermatogenesis of this Annelid. The processes agree entirely with 

 what the authors have described in Tomopteris. 



Sex-Determination in Dinophilus apatris.^f — Hans Freiherr von 

 Maisen finds that in this primitive worm sex-determination occurs in 

 the ovary and depends on the nutrition of the ovocytes. The better 

 the nutritive conditions the more " female " ova are produced. The 

 influence of temperature is not direct, it operates by favouring or 

 inhibiting the nutritive conditions. In general the nutritive conditions 

 are most important, but it is not to be supposed that throughout the 

 animal kingdom this is the only sex-determining factor. There are 

 several co-operative factors, and the period of sex-determination varies 

 from case to case. 



NematolielrQinth.es. 



Abnormalities of Sex Organs in Ascaris.** — H. Balss describes in 

 Ascaris lumhricoides a tripartite uterus, all the divisions of which pro- 

 duced eggs in a normal manner. W. Harms records a case' of a female 

 Ascaris meg aloe ephala, in which the uterus is unpaired, and an example 

 of an Ascaris of undetermined species, also a female, in which the vaginal 

 opening occurs upon the left side in a dorso-lateral position, at the usual 

 distance from the anterior end. 



* MT. Zool. Stat. Neapel, xvii. (1906) pp. 515-23 (2 figs.). 



t Raccolte Planctoniche (R. 1st. Stud. Sup. Firenze) ii. (1906) pp. 53-78 (2 pis.). 

 X Rev. Suisse Zool., xiv. (1906) pp. 185-316 (4 pis.). 

 § Amer. Nat., xl. (1906) No. 478, pp. 683-706 (12 tigs.). 

 |] Anat. Anzeig., xxix. (1906) pp. 465-79 (17 figs.). 

 ^ Arch. Mikr. Anat., Ixix. (1906) pp. 63-99 (1 pi.), 

 ** Zool. Anzeig., xxx. (1906) pp. 485-8. . 



