60 SUMMARY OF CURRENT RESEARCHES RELATING TO 



passes through the in-pushing endoderm into the cavity of the archen- 

 teron. In M. a small amount of "mesoderm" is formed from the 

 developing endoderm cells. The blastopore becomes the mouth, and in 

 early stages is oval or slit-like and slightly to one side. The larva of M. 

 has an aboral tuft of long cilia and an aboral sense-organ. The stomo- 

 dseum forms by in-folding of epiblast at the blastopore, with subsequent 

 elongation by interstitial growth. There is a definite 8-mesentery 

 stage ; the sulco-lateral mesenteries are the first to appear ; the mesenteric 

 filaments contain downgrowths of stomodaeal epiblast. The planula is 

 provided with stinging cells. The young if., prior to aboral fixation and 

 tentacle formation, creeps about, mouth downwards, with the stomodseum 

 more or less everted. It is probable that feeding takes place at this 

 time, as in the immediately preceding late planula stage. It is suggested 

 that the Anthozoa acquired an ectodermic stomodaBum and the rudi- 

 ments of bilateral symmetry during a creeping ancestral stage, from 

 which the Turbellaria and the higher Metazoa may have been derived. 



J.A.T. 



Northern and Arctic Alcyonaceae. — Arvid R. Molander (A". 

 SvensTca VetensTcapsakad. Handlingar.^ 1915, 51, 1-93, 3 pis., 14 figs.). 

 Part of a systematic survey, with special attention to localities and 

 depths. As regards structure, emphasis is laid on the details of the 

 canal-system, on the formation of the calyx, aud on the spicules. 

 Descriptions are given of Anthelia borealis (Dan.), A. fallax Broch., 

 Clavularia arctica (Sars.), C. stormi Dan., Xenia ivandelii Jungersen, 

 Anthomastus j^urpureus (Kor. & Dan.), A. agaricus Studer, Alcyonium 

 digitatum and two varieties, Sympodium catenatum (Forbes), five species 

 of Gersemia and varieties, six species of Eunephthya^ including E. 

 groenlandka sp. n. J. A. T. 



Spitzbergen Alcyonacea. — A. R. Molander {Zool. Ergehnisse 

 Schived. Exp. Spitzbergen, in K. Svenska Vetenskapsakad, Handl.^ 



1918, 54, No. 9, 1-19, 1 fig.). An account is given of Gersemia rubi- 

 formis (Ehrenberg), G. uvaeformis (May), G. clavata (Dan.), G. clavata 



var. crassa (Dan.), G. fruticosa (M. Sars.), G. fruticosa var. rigida 

 Molander, G. mirabilis (Dan.), and Eunephthya glomerata Yerrill. The 

 species of Gersemia are difficult to deal with, and this further study is 

 very welcome. Special attention is given to the distribution of the 

 species. J. A. T. 



New Genus of Tetracoralla. — G. M. Ehlers {Amer. Jonrn. ScL, 



1919, 48, 461-7, 3 figs.). A new genus and species, Heterolasma fctrsteij 

 from the Niagaran of Michigan, seems to represent an aberrant depar- 

 ture from Zaphrentis, differing (like Amplexus) in not having the septa 

 reach the centre of the corallum. The genus is also characterized by 

 its wide tabulae, its shape (a short cone with more or less horizontally 

 extended margins), and the diversity in the form of the septa. J. A. T. 



Development of Colonies of Aglaophenia. — Maurice Bedot {C.R. 

 Soc. Phys. His. Nat. Geneve, 1919, 36, 50-7, 4 figs.). The author 



