ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 323 



shows a marked " nycthemeral " rhythm. This is more marked in the 

 Mediterranean than in the Channel, for in the former the sensitiveness 

 to variations in illumination is very acute. The rhythm persists even 

 after a period of continuous darkness. Light is the determining factor 

 in the rhythm, which the chemical changes only perturb. 



New Species of Cactogorgia.* — J. J. Simpson describes Gactogorgia 

 agariciformis sp. n., a rather striking Alcyonarian (of unknown origin) in 

 the collection of the Royal Scottish Museum, Edinburgh. The other 

 species, four in number, have been recorded from the Indian Ocean. 

 The author contrasts the new species with the others. 



New Pseudaxonid Genus Dendrogorgia.f — J. J. Simpson describes 

 a Jutuella-like Alcyonarian, Dendrogorgia capensis g. etsp. n., from the 

 Cape, which turns out to be a Pseudaxonid. There is a sclerogorgic 

 axis, without solenia, built up of spicules embedded longitudinally in a 

 horny matrix. The thick ccenenchyma is packed with double and triple 

 stars. The canal system consists of an inner longitudinal series separat- 

 ing the axis from the ccenenchyma, and an outer longitudinal series 

 near the periphery, the two being connected by a network of small 

 transverse solenia. The polyps occur all over, and are completely 

 retractile. Hickson's Juncella elongata var. capensis must be included 

 in this type. 



Medusae of the Gulf of Trieste.^ — Valeria Neppi discusses in 

 particular the form without cirri known as Irene pellucida Will, (which 

 is shown to be the same as Geryonia pellucida Will), and the related 

 form without cirri for which the new name Tima plana is suggested. 



Life-cycle of Eleutheria.§ — Du Plessis has succeeded by the method 

 of isolation in observing, what has hitherto baffled observers, the complete 

 alternation of generations in this hydroid — in other words, the Eleutheria 

 and the Glavatella stages. He also points out that the common Eleu- 

 theria of the Mediterranean is different from E. dichotoma, and proposes 

 E. gemmipara as its name. 



New Gymnoblastic Hydroid Epizoic on a Pennatulid.|| — Winifred 

 E. Coward describes Ptilocodium repens g. et sp. n., growing on the tips 

 of the pinnules of Ptilosarcus sinnosus. It is a very remarkable form, 

 seeming to have some affinities with Hydractinia, Podocoryne, and Mille- 

 pora, as shown by the sheetdike, encrusting basal ccenosarc, from which 

 the zooids arise independently ; but even in this character it stands alone 

 in having no chitinous or calcareous skeleton to support it. 



Moreover, it is peculiarly dimorphic. The gasterozooids are short, 

 sessile, sac-like structures without tentacles. The dactylozooids are short 

 and broad, with four characteristic capitate tentacles. There are adelo- 

 codonic gonophores arising from the base of the ordinary gasterozooids. 

 In fact, this new type stands quite apart, and requires a family for itself. 



* Proc. Roy. Soc. Edinburgh, xxx. (1910) pp. 324-6(1 pi.). 



t Proc. Roy. Phys. Soc. Edinburgh, xviii. (1910) pp. 62-7 (4 figs.). 



X Arbeit. Zool. Inst. Wien, xviii. (1910) pp. 157-66 (5 figs). 



§ Rev. Zool. Suisse, xvii. (1909) pp. 371-7. 



|| Proc. Section of Sciences Akad. Amsterdam, xi. (1909) pp. 635-41 (1 pi.). 



z 2 



