G4 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Annulata. 



New Polygordius.* — Akira Izuka describes Polygordius Ijimai, a 

 new species from Misaki,: Japan. The discovery is noteworthy, since 

 all the species hitherto known are from the coasts of Europe. The 

 members of this species, both male and female, are of a light pink colour. 

 On each side of the head, at about the level of the mouth, an oval-shaped 

 vibratile pit is found. The musculature of the body wall is peculiar in 

 not having circular muscle fibres, while in the intestinal wall neither 

 longitudinal nor circular muscles are to be found. The vascular svstem 

 is peculiar in having the dorsal and the ventral vessel connected by a pair 

 of lateral loops in each segment. A point worthy of notice is that the 

 species is nearly sexually mature as early in the season as the end of March. 



Development of Phascolosoma.f— J. H. Gerould, in a preliminary 

 note, summarises the results of his studies on the development of Phas- 

 colosoma. They throw light on the hitherto apparently anomalous 

 development of Sipunculus. Phascolosoma is in most respects less 

 highly modified, and is more like the Annelids. Numerous features, 

 e.g. a transitory metamerism of the mesoblastic bands, and of the nerve- 

 cord in the trochophore, indicate close relationship between the Sipun- 

 culids and Annelids. Sipunculids are to be regarded as forms that have 

 recently sprung from the ancestral trochozoon. The adult Sipunculid 

 retains the retractor muscles and nephridia of the trochophore. The loss 

 of the prototroch, the development of the coelome, and the enormous 

 elongation of the trunk, are the only fundamental changes which the 

 trochophore undergoes in passing into the adult condition. 



Histology of Ctenodrilus Clap. J — Egon Galvagni has made a de- 

 tailed comparative study of the two species of Ctenodrilus, dealing 

 principally with details of the vascular system, nephridia, and pharynx 

 previously incorrectly described, and with other features, e.g. circular 

 muscles, pigment, and mucous cells, etc. He concludes that the cha- 

 racters of the nervous system, etc., and in particular the nature of the 

 bristles, suggest relationship to the Cirratulids, and decides in favour of 

 classing the genus under this family. 



Musculature of Branchiobdell aparasitica.§— F. Schmidt finds the 

 musculature of this parasite, in relation to its extremely sluggish and 

 leisurely movements, feebly developed. The muscle cells are of the 

 primitive nematoid type, i.e. the myoblast is surrounded by a contractile 

 tegument, which is interspersed with either widely-gaping or narrow 

 slit-like fissures, into which the protoplasm of the myoblast is continued. 

 The myoblast consists of plasma and a nucleus. The contractile tegu- 

 ment contains radiating layers of fibrils, which consist of colourable and 

 uncolourable longitudinally-placed columns. There are notably two 

 types of muscular cells, a cylindrical and double cylindrical type. 



Anatomy and Histology of Myzostoma.|| — R. Eitter v. Stummer- 

 Traunfels, in view of the fact that descriptions of species of this genus 

 contain a series of errors, due to the neglect of internal characters in 



* Annot. Zool. Japon, iv. (1903) pp. 137-9. 



t Arch. Zool. Exp., ii. (1904); Notes ct Revue, No. 2, pp. xvii-xxix. 



% Arbeit. Zool. Inst. Uuiv. Wien, xv. (1903) pp. 1-31 (2 pis.). 



§ Zeitsch. f. Wiss. Zool., Ixxv. (1933) pp. 59G-705 (1 pi., 13 figs.). 



|| Tom. cit., pp. 495-595 (5 pis ). 



