316 SUMMARY OF CURRENT RESEARCHES RELATING TO 



complete in Cambrian rock. Crater-like orifices were seen precisely like 

 those of the burrows of littoral Polychastes. A form with a larger tube 

 in Siluro-Cambrian limestone was referred by Torell to his genus Mono- 

 craterion. 



Phascolosoma minutum.* — Georg Paul gives an account of Petalo- 

 stoma minutum Keferstein, Phascolosoma sabellarise Theel, and P. 

 improvisum Theel, and shows that they must be merged in P. minu- 

 tum Keferstein. Perhaps P. anceps will have to follow. It is pointed 

 out that P. minutum is hermaphrodite, the only certain case among 

 Sipunculids. The author has also some notes on the structure of Onche- 

 soma steenstrupi. 



Parthenogenesis in Dinophilus conklini.f — Paul de Beauchamp 

 finds that the nanism of the males is associated in this species with in- 

 dubitable parthenogenesis. But this can only go on for several genera- 

 tions in the absence of males, and leads to a degeneration of the stock. 

 This is very interesting in itself, and also in connection with the probable 

 relationship between Dinophilus and Rotifers. 



Nephridia of Dinophilus and of Larvae of Polygordius, Echiurus, 

 and Phoronis4 — E. S. Goodrich describes in Dinophilus a new type of 

 solenocyte formation, representing perhaps an intermediate step between 

 the Platyhelminth " flame-cell " and the more typical Polychaste sole- 

 nocyte, in which each tube, with its flagellum, has its own nucleus. This 

 latter state might be reached by a multiplication of the nuclei until they 

 came to correspond in number with the tubes. That Dinophilus is re- 

 lated to Polygordms has long been suspected ; and it is interesting to 

 note that in the larval nephridium of Polygordms there is a similar 

 multiplicity of tubes. In P. neapolitanus a single nucleus, at the tip of 

 each branch of the nephridial canal, controls a set of from six to seven 

 solenocyte tubes. " The canal and solenocytes of the Annelid nephridium 

 form a whole, a single organ derived from one rudiment, strictly com- 

 parable to the canal and flame-cells of the platyhelminth excretory organ." 

 The author also discusses the solenocytes seen in the larvae of Echiurus 

 and Phoronis. 



Oogenesis of Sagitta.§ — Paul Buchner gives an account of the 

 oogenesis in Sagitta, with some notes on maturation and fertilisation. 

 The unequivocal persistence of the ovum chromosomes throughout the 

 whole oogenesis is emphasized. 



Australian Hirudinea.|| — E. J. Goddard continues his studies on 

 Australian Hirudinea, describing Glossiphonia intermedia sp. n., G. 

 heteroclita (?), and Limnobdella australis. It is pointed out that the 

 structure of the genital apparatus in Glossiphonia strengthens the view 

 that the members do not copulate. Whitman has shown that hypodermic 

 impregnation obtains in G. parasitica. It is interesting that all members 



* Zool. Jahrb., xxix. (1909) pp. 1-50 (2 pis.). 



f Coniptes Rendus, cl. (1910) pp. 789-41. 



% Quart. Journ. Micr. Sci., liv. (1909) pp. 111-18 (1 pi.). 



§ Anat. Anzeig., xxxv. (1910) pp. 433-43 (17 figs.). 



|| Proc. Linn. Soc. N.S.W., xxxiv. (1909) pp. 467-86 (2 pis.). 



