590 SUMMARY OF CURRENT RESEARCHES RELATING TO 



differentiation, since in do instance was a differentiated, ciliated structure 

 observed which was unsegmented ; the parthenogenetie pseudo-trocho 

 phores which have been described for GhcBtopterus and other Annelids, 

 are entirely absent. 



Remarkable Echiuroids* — Iwajilkeda describes Bonellia miyajimai 

 sp. n., the female of which has numerous ventral hooks, a slender 

 proboscis six times as long as the body, and branched anal glands with 

 numerous stalked funnels. The male, found in the body-cavity of 

 the female, is unusually large, nearly 30 mm. in length : there is no 

 ventral hook or nerve ring ; the alimentary canal is broken up into 

 numerous vesicles. He also describes two new species of Thalassema : 

 T. timioides, the long proboscis of which has been known and misin- 

 terpreted for some years, and T. elegans, another very interesting form. 



New Indian Oligochset.f — J. Stephenson proposes to make a new 

 genus, Mafia, for one of the Naididge, which was found on colonies of 

 Victorella and other Polyzoa. The arrangement of the setal bundles is 

 peculiar : there are two dorsal and two ventral bundles in all segments 

 from the second onwards. The seta? are hook-seta3 and needle-seta^ ; the 

 most anterior bundles, both dorsal and ventral, consist of needle-setse ; 

 the posterior consist of hook-setae. 



Studies on Leeches.! — N. Livanow has studied the nervous system 

 and the metamerism of the head-end of Herpobdella atomaria Carena. 

 The head-region consists, as in Hirudo medicinaUs and Protoclej/s/s 

 tessellata, of the head-lobe and the five anterior somites. The head-lobe 

 and the first two head-somites consist of one ring each, the third has two 

 rings, the fourth has four, and the fifth has five. In each somite there 

 is a well-developed neuro-somite, and the head-lobe is in no way con- 

 fusible with a somite. 



New Zealand Leeches.§ — W. B. Benham describes Placobddla 

 maorica sp. n., Hirudo mauiana sp. n., and H. antipodum Benham, giving 

 in each case an anatomical account. 



Growth and Asexual Reproduction in Stylaria lacustris.|| — 

 Giuseppe Dalla Fior has studied the process of growth in this Annelid, 

 which is also known as Nais proboscidea. The mesoderm grows at the 

 free posterior end by the activity of primitive mesoblasts, of which there 

 are two or three on each side of the hind end of the mesoderm streak. 

 Before the division of the mesoderm into primary segments, the chorda - 

 cells of Semper (neoblasts) arise between the two mesoderm plates. These 

 elements always retain an embryonic character, and form a continuous 

 strand to the most anterior segment. 



In asexual multiplication the mesoderm in the trunk-zone (the tail 

 of the anterior animal) is mainly regenerated by the neoblasts, and only 

 to a slight extent by the mesodermic elements of the lateral lines. In 



* Journ. Coll. Sci. Univ. Tokyo, xxi. (1907) pp. 1-64 (4 pis.). 



t Records Indian Museum, ii. (1908) pp. 39-42 (4 figs.). 



t Zool. Jahrb.,xxiii. (1907) pp. 683-702 (1 pi ). 



§ Trans. New Zealand Inst., xxxix. (1907) pp. 181-93 (2 pis.). 



|| Arbeit. Zool. Inst. Univ. Wien, xvii. (1908) pp. 109-38 (2 pis.). 



