176 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Rome details at least. Evidence is given in support of the view that the 

 Halecidae diverged at an early stage from the Thecaphora stem which 

 bears Campanularians and Sertularians, and that the Halecidae lead on 

 to the Plumularians. 



Cnidoblasts of Hydra.* — 0. Toppe finds that the large pyriforui 

 cnidoblasts with stilets on the nematocyst play the most important part 

 in capturing prey. The nematocyst, helped by the stilets, perforates 

 the cuticle of a Corethra larva, and the secretion acts rapidly "and destruc- 

 tively, forming a depression. There is no doubt that the nematocyst, 

 partly by boring, partly by dissolving, can work through a chitinous 

 membrane of considerable thickness. The large cnidoblasts work for 

 the most part mechanically, and they seldom miss the mark. The nema- 

 tocysts of the small cnidoblasts coil up in a corkscrew spiral after explo- 

 sion, and they seem to respond to a different kind of stimulus. Thirdly, 

 there are cylindrical cnidoblasts which aid in the attachment of the 

 tentacles or the proboscis. 



Medusoids, Medusas, and Ctenophores of Firth of Forth.j — Win. 

 Evans and J. H. Ashworth record the following Hydromedusae : — Mar- 

 gelis britannica Forbes, Sarsia tubulosa Sars, Melicertidium octocostatum 

 Sars, Tiaropsis multicirrata Sars, Mitrocomella polydiademata Eomanes, 

 Eutonina socialis Hartlaub, Timet bairdii Johnston, JEnuorea norvegica 

 Browne. Of Scyphornedusae they collected Gyanea capillata Linn., and 

 Aurelia aurita Linn. ; of Ctenophores, Pleurobrachia pileus Fab., Bolina 

 infundibulum Fab., and Beroe cucumis Fab. 



Nervous System of Anemones. $ — Paul Groselj has studied numerous 

 Actinians — such as Actinia equina, Cerianthus membranaceus, Adamsia 

 paJUala, Bunodes gemmaceus — with respect to the minute structure of the 

 nervous system. He describes the sensory nerve-cells (both ectodermic 

 and endodermic), the ganglion-cells, and the processes of both. Attention 

 is directed to the incipient centralisation to be seen in the ectoderm of 

 the gullet, where the nerve-fibre layer is strongly developed ; the sensory 

 nerve-cells are very abundant : their processes form a very intricate 

 ramification ; there is extraordinary abundance of tripolar and multipolar 

 ganglion-cells, which are arranged in radial bands and form a rich plexus 

 of processes. 



Zoanthese from Queensland and New Heurides.§ — Leonora J. 

 Wilsmore describes Zoanthus sandvicensis sp. n., Z. similis sp. n., Z. pig- 

 mentalus sp. n., and Gemmaria arenacea sp. n. The abundance of yellow- 

 brown pigment in Z. pigmentatus is very striking. At the same time, 

 zooxanthellae are as abundant as in Z. sandvicensis and Z. similis, in which 

 there is very little pigment. It seems, therefore, that the relationship 

 between zooxanthellae and pigment-granules, in virtue of which they re- 

 place one another in the genus Parazoanthus, and in several families of 

 Actinaria, does not exist in these species. 



* Zool. Anzeig., xxxiii. (1909) pp. 798-805 (7 figs.). 



t Proc. R. Phys. Soc, xvii. (1909) pp. 300-11 (1 fig.). 



j Arbeit. Zool. Inst. Univ. Wien, xvii. (1909) pp. 269-308 (1 pi. and 22 figs.). 



§ Journ. Linn. Soc, xxx. (1909) pp. 315-28 (3 pis.). 



