38 SUMMARY OF CURRENT EESEAECHES RELATING TO 



small individuals, but degenerate in large ones, and believes that its 

 function is to increase the secretory surface in the small individuals 

 which have a relatively short gut. In the brain four types of nerve-cells 

 were made out in addition to neuroglia-fibres and cells. The author 

 makes no suggestion as to the affinities of Sipunculus. 



Study of English Channel Polychaets.* — Mr. T. V. Hodgson brings 

 into compact form the records of those Amphinomidae, Aphroditidae, 

 Polynoidse, and Sigalionidas, known to occur in the Channel, and gives 

 descriptions of species and synoptical tables which will be of service to 

 other workers. The section dealt with is that treated of by MTntosh 

 in the recently published part of his monograph, to which Mr. Hodgson 

 acknowledges his indebtedness. 



Arenicola.'t" — Dr. P. Fauvel gives an account of the structure and 

 habits of lob-worms, and discusses their distribution and systematic 

 relations. There is only one genus constituting the family Arenicolidte ; 

 Brancltiomaldane and Arenicolides are not justifiable genera. The family 

 shows no transitions towards the Maldanidaa. The most primitive species 

 is A. ecaudata, one of the most evolved is A. claparedii, while A. vincenti 

 is degenerate. 



Anatomy and Classification of Arenicolidae. J — Messrs. F. W. 

 Gamble and J. H. Ashworth fiud that there are three British species 

 of Arenicola, A. marina, A. ecaudata, aud A. grubii. In addition there 

 are two other species, A. claparedii, Mediterranean and Pacific, and 

 A. cristata, Mediterranean, Florida, and Jamaica. The American forms 

 described as A. natalis Gir. and A. arenata both belong to the species 

 A. marina. Audouin and Milne-Edwards' species A. branchialis was 

 possibly founded on specimens of A. grubii ; but as the type specimens 

 are lost, and the descriptions insufficient, the species should lapse. The 

 five recognisable species fall into two groups, A. ecaudata and A. grubii 

 differing from the other three in the absence of a tail, the simple pro- 

 stomium and brain, the shape of the nephridia, and some other points. 

 In regard to specific characters, the authors fiud that the most reliable 

 are founded on the characters of the otocysts, prostomium, and nephridia 

 taken together, and they give diagnoses depending on these points. The 

 external characters are subject to great variation in all the species. The 

 authors have also made a number of observations on the anatomy of 

 the different s])ecies, and on the post-larval stages. Among the most 

 striking of their results are the following. Giant-fibres and segmentally 

 arranged giant-cells occur in the nerve-cord of all the species except 

 A. claparedii. All the species possess eyes during at least the immature 

 stages ; they are superficial in the larva, but sink in until in the adult 

 they are found among the ganglionic cells of the brain. The Areni- 

 colidae show most affinity with the Maldanidae, but nevertheless form a 

 well-defined group. Special mention should be made of the figures, 

 which are numerous and clear. 



Affinities of Procerastea (Langerhans). § — Ch. Gravier obtained 

 four specimens of a new species of this genus in the Bay of La Hougue, 



* Journ. Mar. Biol. Ass., vi. (1900) pp. 218-5'.). 



t Mem. Soc. Sci. Nat. Cherbourg, xxxi. (1898-1900) pp. 101-SG (11 figs.). 

 I Quart. Jouru. Micr. Sci., xliii. (1900) pp. 119-569 (8 pis.). 

 L § Ann. Sci. Nut. (Zool.), xi. (1900) pp. S5-50 (1 pi.). 



