ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 619 



stage — or more precisely speaking, those of the first quartet — fail in 

 some cases to develop comb-rows, the importance of correlative differ- 

 entiation should not be overlooked in the development of the Ctenophore 

 egg. In rare cases the distribution of the ctenoplasm among the blasto- 

 meres of the eight-cell stage may vary so that the number of comb-rows 

 is greater than that of the initial blastomeres. \ 



Ctenophores of Atlantic Coast of North America.* — A. G. Mayer 

 gives a beautifully illustrated account of twenty-one Ctenophores from 

 the Atlantic coast of North America. Four of these are new to science ; 

 seven have not hitherto been recorded with certainty ; six are Mediter- 

 ranean species which extend across the tropical Atlantic to the American 

 coast. The author calls attention to the physiological evidence that 

 there is a nervous system in Ctenophores, as Bethe has maintained on 

 the ground of histological data. In Ctenophores when the muscles con- 

 tract the cilia cease to beat, being inhibited by the stretching of the 

 ciliated epithelium. A solution of magnesium chloride, which inhibits 

 muscular movement and produces relaxation, causes an incessant, and 

 very active movement of the cilia. 



Dictyonema Fauna. f — F. F. Hahn discusses the structure and 

 probable mode of life of the Graptolite, Dictyonema flalelliforme, and its 

 varietal range. He argues that the route of evolution started from a 

 holoplanktonic mode of life, and passed through a partly epiplanktonic 

 to a definitely sessile habit. 



Porifera. 



Clare Island Sponges.^ — Jane Stephens reports on 64 species 

 collected off Clare Island and along the coast of the adjacent mainland. 

 Twenty are recorded for the first time for the Irish coast, and seven have 

 not previously been recorded from the British Isles. A description is 

 given of Leucandra cliarensis sp. n., which is easily distinguished at 

 sight from all other species of Leucandra hitherto found off the shores 

 of the British Isles by the presence of large dermal monaxon spicules, 

 which lie for the most part parallel to the long axis of the sponges. 

 These spicules can be seen with the naked eye ; they give a characteristic 

 silvery-white appearance to the sponge. A second new form is Gellius 

 ravus sp. n., which differs from G. angulatus (Bowerbank) in the length 

 of the oxea, the shape of the toxa, and the structure of the dermis. 



Australian Sponges. § — E. F. Hallmann gives an account of a large 

 number of Monaxonellid sponges collected by F. I. S. ' Endeavour' on 

 the coasts of Australia. Many new species are described, and particular 

 attention is devoted to the spicules. 



* Carnegie Inst, of Washington, Publication No. 162 (1912) 58 pp. (17 pis. and 

 12 figs.), 



t Ann. New York Acad. Sci., xxii. (1912) pp. 135-60 (3 pis.). 



X Proc. R. Irish Acad., xxxi. (1912) Part 59, pp. 1-42 (1 pL). 



§ Zool. Results of Fishing Exper. carried out by F. I. S. ' Endeavour,' 

 Part 2, Sydney (1912) pp. 117-300 (pis. xxi.-xxxvi., figs. 21-69. 



