180 SUMMARY OF CURRENT RESEARCHES RELATING TO 



several parts of the system (brain, oesophageal ring and commissures) are' 

 not re-made separately, but from unified paired ectodermic primordia. 

 The regenerative processes agree with the embryonic development in 

 having this paired origin. The author has many general remarks of" 

 much interest, e.g. that the regeneration-process does not show any 

 distinct mesoderm-diff erentiation . 



New Species of Alma.* — 0. Duboscq describes Alma zebanguii sp. n. 

 from a tributary of the Oubangui, Africa. He directs special attention 

 to the large solid paired penis with glands and suckers, to the diverti- 

 cula of the oesophagus, to the typhlosole, to the clitellum, and to the 

 setse. He distinguishes three stages : — an immature form without penis, 

 an adolescent form with penis but without clitellum, and a mature form 

 with clitellum. The genus Alma includes five species, of which Alma 

 nilotica alone has branchiae and is palasarctic ; the non-branchiate species 

 are Ethiopian. Perhaps the genus should be split into two. Affinities 

 with Glossoscolecidae seem certain, but perhaps it will be found necessary 

 to make a new sub-family Alminae for the African species. 



Hemiclepsis and allied G-enera.f — N. Livanow finds that the re- 

 presentatives of the genus of leeches known as Hemiclepsis, fall into two 

 groups, one set grouped round H. tessellata and approaching the 

 Glossosiphoniae ; the other set grouped round H. marginata, and in 

 some respects approaching the Ichthyobdellids. For the former he 

 proposes the new genus Protoclepsis, and describes four new species. 

 The new genus is to some extent a connecting link between Hemiclepsis 

 on the one hand and Glossosiphonia (along with PlacoMella and Hamen- 

 teria) on the other. 



Nematohelminth.es . 



Species of Rhabditis.f — A. Michel has tried to distinguish in his 

 cultures some of the species in this difficult genus. He finds a herma- 

 phrodite form, described by Vernet under Dujardin's title Rh. terricola, 

 a name afterwards replaced (by Maupas) by the title Rh. verneti, since 

 Dujardin's type was dioecious. He finds also a dioecious form, which is 

 in many ways like Rh. terricola, but also like Rh. dolichura which is, 

 however, smaller and oviparous. A third form seems to be Rh. elegans 

 Maupas, and a fourth the parthenogenetic Rh. schneideri. 



Hind-End of Ascaris. — E. Voltzenlogel has studied the posterior 

 region of A. megalocephala and A. lumhricoides. There is a glandular 

 ring round the beginning of the hind-gut, consisting of six cells in the 

 male, of three in the female. The dilators of the chyle-intestine and 

 the compressor of the ductus ejaculatorius are formed by the same 

 muscle-cells, two in number. 



The spicula are more than setae. With their sheaths they represent 

 a continuation of the body-wall, including both cuticula and sub-cuti- 

 cula. The latter is the more important in the formation of the spicule. 



* Arch. Zool. Expe'r., x. (1902) Notes et Revue, No. 7, pp. xcvii.-cvi. (3 figs.). 



+ Zool. Jahrb.. xvii. (1902) pp. 339-62 (1 pi.). 



t Comptes Rendus, cxxxv. (1902) pp. 907-10. 



§ Zool. Jahrb., xvi. (1902) pp. 481-510 (3 pis.). 



