534 SUMMARY OF CURRENT RESEARCHES RELATING TO 



neptuni very closely in all those points in which it differs from the 

 Japanese form. These facts seem to render a redistribution of the 

 species into genera necessary. 



Annelids from Patagonia and Chile.* — Prof. E. Ehlers describes the 

 Annelids of Plate's expedition. The collections include sixty-five species, 

 of which over twenty are new. These are briefly described here, and are 

 to be discussed more fully later. 



Supra-oesophageal Ganglia of Lumbricus agricola.f — J. De Meyer 

 distinguishes: — (A) a palpar region including (1) a pair of internal 

 ganglia forming an "anterior brain,'' (2) a pair of external superior 

 nerves, (3) a palpal area with tactile structures, and (4) the internal 

 roots of the peri-cesophageal connectives; and (B) a syncipital region 

 including (1) peripheral ganglia forming a " posterior brain," (2) a pair 

 of internal inferior nerves, (3) a syncipital area with optic and tactile 

 organs, and (4) the external roots of the peri-cesophageal connectives. 

 These two regions are the homologues of the palpar and syncipital re- 

 gions in Polychsetes ; the nuchal region is undeveloped. 



Oligochsetes of Switzerland.! — Dr. K. Bretscher has continued his 

 observations -on this subject by a survey of some new districts. The 

 survey has not only resulted in the discovery of some new species, but 

 has also shed some light on the causes influencing distribution. The first 

 factor determining the distribution, especially of tbe Enchytraaidie, is 

 the amount of water present in the soil, the worms being intolerant of 

 dryness. The geology of tbe district influences its Oligochaete fauna 

 in so far as it affects the depth of soil. Thus the Goschenalp has a 

 very shallow crust of soil, and is remarkably poor in worms. The 

 author also discusses some of tbe interesting questions connected with 

 the fauna of the small Alpine lakes, liable alike to be dried up in 

 summer and frozen in winter. 



Nematohelminthes. 



Modes of Reproduction in Nematodes. § — E. Mauj>as has made a 

 biological study of much importance on numerous species of nematode 

 worms. (1) In 18 species, 16 of which are new, distinct males are 

 absent ; out of a total of 34 species reported on by Mau pas and others, 

 25 are hermaphrodite, and 9 are parthenogenctic. (2) Neither the 

 hermaphrodite nor the parthenogenetic forms show any structural 

 peculiarity except as regards the gonads, but all have a feminine aspect. 

 Three species, Rhabditis elegans, It. caussaneli, and Diplogaster robustus, 

 are ovo-viviparous ; the rest are oviparous, but the eggs may have to 

 undergo 3 or 4 or all of their cleavages before liberation. (3) The 

 hermaphrodites are protandrous (proteraudric) and autogamous. (4) The 

 hermaphrodite forms produce (a) spermatozoa, which are stored in tbe 

 seminal receptacle of the uterus, (b) a number of eggs which are ferti- 

 lised, and (c) a larger number (§- or more of the total) which are not 

 fertilised and simply abort. It seems as if the male, or rather the 



* Zool. Jahrb., Supp. v. vol. ii. (1901) pp. 251-72. 



t Ann. Soc. Beige Microsc, xxvi. (1899-1900, published 1901) pp. 146-64 

 <3 figs.). J Eev. Suisse Zool., ix. (1901) pp. 189-223 (1 pi.). 



§ Arch. Zool. Expe'r., viii. (1900) pp. 463-624 (.11 pis.). 



