1000 SUMMARY or CURRENT RESEARCHES RELATING TO 



various genera. Supporting Lankester's position, Mr. Beddard re- 

 views the diiSculties suggested by Perrier, that nephridia and 

 copulatory pouches occasionally coincide at the same seta, and that 

 the vasa deferentia pass through several segments each with distinct 

 nephridia. But Mr. Beddard extends Lankester's statement by 

 affirming tlie probability, suggested by the present and other in- 

 stances, that to each seta, and not to each pair of setae, there corre- 

 sponds a separate nephridium. 



In regard to the question whether a quadri-serial arrangement of 

 setae comparable with the Polychaetous parapodia, or a complete ring 

 of setae as in Perichaeta, is the more primitive state, Beddard inclines, 

 against Perrier, to the latter supposition. While, on the one hand, 

 the two pairs of setae in the earthworm certainly resemble the dorsal 

 and ventral parapodia of a Polychaete, and while the young Perichaeta 

 have not a complete ring of setae as in adults, he points out, that in 

 the Urochaeta the setee, anteriorly in eight rows, are posteriorly 

 quincuncial, and have between them small glandular bodies, which 

 from their analogy with similar structures in the Anachaeta evidently 

 replace setae, previously therefore more abundant, and that further 

 since from the above results there seems to be no connection between 

 the pair of setae and the nephridium, as there is in the Polychaeta 

 between parapodium and nephridium, the resemblance is more pro- 

 bably adaptive than genetic, and the more generalized condition is 

 probably the more primitive. 



Organization of Pachydrilus enchytrseoides.* — M. Eemy Saint- 

 Loup describes this small Annelid, which is found abundantly on 

 algae at Marseilles, as having four rows of setfe, two to eight in each 

 group ; these setae are not hooked at their ends. There are about 

 thirty-five segments ; the anus opens at the base of a funnel-shaped 

 cavity. There is a dorsal and a ventral blood-vessel, united at either 

 end, and there are three pairs of anastomosing canals. The oesophageal 

 is the only differentiated portion of the digestive tract, but the 

 hinder has a smaller number of "hepatic cells" than the median 

 portion. The coelom is divided into compartments by incomplete 

 septa. The nerve-chain has the ganglia in the segments behind the 

 first three reduced to mere swellings of the cord. In the fifth, sixth, 

 and seventh segments there are large glands which occupy the whole 

 of the body-cavity, and appear to be analogous to the septal glands of 

 Vejdovsky. 



Parasite of the Rock Oyster.j — Mr. W. A. Haswell, on examin- 

 ing some samples of oysters which were dying in large numbers, 

 found that most of them, when opened, presented on the inner surface 

 of the shell one or more discoloured blisters. In some these were 

 of small extent with a narrow sinuous form, while in many instances 

 a large part of the valve was affected. In some cases, where the 

 extent of the shell invaded was not large, the oysters did not seem 

 at all affected by it ; in other cases the animal was found to be dead, 



* Oomptea Eendus, ci. (1885) pp. 482-5. 



t Proo. Liun. Soc. N. S. Wales, x. (1885) pp. 273-5. 



