648 SUMMARY OF CURRENT RESEARCHES RELATING TO 



condition of Halcampa chrysanthellum and H. arenarea. These mesen- 

 teries grow larger, and other pairs appear successively in every exocoele 

 until a considerable number is developed. 



The relationship of the Hydra-tuba and Scyphostoma stages of the 

 ScyphomedusEB (Acalephge) to the Zoantbaria is now generally admitted ; 

 a permanent octoradiate condition occurs in Edwardsia, but it is difficult 

 to see where the Octocoralla (Alcyonaria) fit in. The time for a classifica- 

 tion or phylogeny of the Actiniae as a whole, has not yet arrived, but the 

 table (see preceding page) shows the line of development of some cif them. 



Above the black line new mesenteries arise in pairs within each 

 exocoele, and radially ; below it the mesenteries appear in pairs 

 bilaterally with respect to the long axis of the oesophagus. 



Actinology of the Bermudas.* — Dr. J. P. McMurrich gives an 

 account of the Actinians collected by Prof. Heilprin in the Bermudas. 

 Aijptasia cannot be separated from the Sagartidse, and as it has gonads 

 on the first order of septa, the definition of the family given by 

 E. Hertwig must be amended so far as the statement that the principal 

 septa only are perfect and at the same time sterile is concerned. 

 Condylactis passiflora has grass-green tentacles, owing no doubt to the 

 enormous number of zooxanthellae contained in the endoderm. The 

 author not only considerably amends Andres' definition of the family 

 Phyllactidae, but removes it from the Stichodactylinse to the Actiniae. A 

 new genus — Diplactis — is formed for two new species in which the fronds 

 have a tentacular appearance, so that it seems as if there were two series 

 of tentacles, an inner and an outer. Mammilifera tuberculata is peculiar 

 for the presence of zooxanthellge in its ectoderm ; as a rule these bodies 

 are found only in the endoderm in adult Actiniae. It is possible that 

 their presence is due to the thick cuticle and subcuticula preventing a 

 rapid aeration of the ectoderm cells, and so, by favouring the accumula- 

 tion to a certain extent of carbonic acid, producing favourable conditions 

 for the growth of the parasitic algae. 



Angelopsis.t — Mr. J. W. Fewkes discusses the relationship of 

 Angelopsis to certain Siphonophora taken by the ' Challenger,' and 

 makes some severe remarks on Prof. Haeckel's report on those animals. 

 He points out that he was the first to give an account of an Auronectid, 

 " the revelation of which group Haeckel styles ' one of the most 

 splendid discoveries of the ' Challenger.' ' " 



Porifera. 



Structure of Flagellated Chambers in Sponges. J — Dr. E. v. Len- 

 denfeld points out that in all existing descriptions and figures of the 

 flagellated chambers of sponges, with the exception of those lately pub- 

 lished by SoUas and by Dendy, it is explicitly or implicitly stated that 

 the flagellated chambers are spaces in the sponge, on the surface of 

 which the collared cells stand. This, however, is not so, for the space 

 between the collared cells is filled by a transparent substance which is 

 very similar to the ordinary ground-substance of the intermediate layer 

 of sponges. In other words, the collared cells do not stand freely on 

 the surface of the intermediate layer, but are sunk into it. As a rule, no 



* Proc. Acad. N;.t. Sci. Philad., 1889, pp. 102-26 (2 pis.), 

 t Ann. and Mag. Nat. Hist., iv. (1889) pp. 146-55 (3 figs.). 

 X Zool. Anzeig., xii. (1889) pp. 361-2. 



