ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 429 



results. Convoluta roscoffensis is hatched colourless, and at this stage 

 contains neither green cells nor antecedents of green cells. Infection 

 takes place from sea-water or from the egg-capsule to which the infect- 

 ing organism is chemotactically attracted, and on which it habitually 

 settles down and develops. Experiment shows that the green cells of 

 adult Convoluta are incapable of life apart from the body of the animal ; 

 histological examination — proving that the development of the green 

 cell within the body is accompanied by degeneration of its nucleus — 

 supplies the explanation. The infecting organism has been isolated, and 

 by the addition of it to colourless Convoluta the green animal has been 

 synthesised. The green cells serve as an excretory system to the animal ; 

 the relation between them and the animal changes with their develop- 

 ment, passing from symbiosis to parasitism of the animal on the algal 

 cells. The association leads to marked changes of habit on the part of 

 the animal, e.g. to its ceasing from the ingestion of food. The green 

 oell shows the essential characters of the Chlamydomouadeae, and may 

 be provisionally placed in the genus Carteria. 



New Species of Nectonemertes.* — Mary R. Cravens and Harold 

 Heath describe the structure of Nectonomertes pelagica sp. n., from off 

 the Californian coast. The variations in their specimens are fully as 

 great as those separating N. mirabilis and N. grimaldii. It is pointed 

 out that Nectonemertes resembles Amphiporus in several fundamental 

 particulars, and the authors are inclined, with Biu'ger, to believe that the 

 two have had a common progenitor. 



Incertae Sedis. 



Plumes of Cephalodiscus.f — W. Gr. Ridewood has investigated the 

 development of these in three recently discovered species, as well as in 

 C. dodecalophus, and concludes that the torsion of the axes of the first 

 and second plumes of the buds described by Masterman does not take 

 place. The grooved faces of the axes of these plumes remain directed 

 towards the dorsal face of the buccal shield throughout life. The last 

 two pairs of plumes do not arise between the first two pairs of plumes 

 and the buccal shield, as described by Masterman, but they arise on the 

 dorsal side of the plumes, i.e. the side remote from the shield. Harmer's 

 contention that the series of plumes and post-oral lamella are continuous, 

 is borne out. Separate accounts are given in the paper of the plume 

 development in buds of C. hodgsoni, G. dodecalophus, C. nigrescens, and 

 C. gilchristi. 



New Species of Cephalodiscus.|— W. G. Ridewood gives a careful 

 description, with numerous figures, of C. gilchristi sp. n., dredged by 

 Gilchrist at the Cape in about '40 fathoms. The polypides, which are 

 male and female, inhabit separate cavities (suli-genus Idiothecici) ; there 

 are six pairs of plumes ; the buccal shield has a broad dark margin, 

 and the tubarium bears long spines. A key is given for the identifica- 

 tion of the seven species of Cephalodiscus now known. 



* Zool. Jahrb., xxiii. (1906) pp. 387-56 (2 pis.). 



t Quart. Journ. Micr. Sci., No. 202 (1907) pp. 221-52 (11 figs.). 



X Marine Invest., South Africa, iv. (1907) pp. 173-92(3 pis.). 



