412 SUilMAKY OF CURRENT RESEARCHES RELATING TO 



von Koch, that the corallum is derivecl j)rimitively from the basal ectoderm, 

 and that the theca is formed by the fused peripheral parts of the septa, 

 which in fusing divide the mesenteries, and leave a portion of the ccelenteron 

 external to the theca. During life the animal constantly closes the middle 

 portion of its mouth, apertures being left at either end by whicb water 

 passes in and out. 



The histological characters of Fungia are simple and conform to the 

 Actinian type. Dealing specially with the mesoglcea of the Coelenterata, 

 the new name appears to be justifiable on the ground that the tissue does 

 not seem to be homologous with the mesoblast of the Triploblastic Metazoa ; 

 in the Hydromedusas it is a fine, apparently structureless membrane placed 

 between endoderm and ect iderm ; in the Siphonophora it is a struc- 

 tureless jelly-like substance ; in the Scyphomedusse it is structureless, 

 but has a fibrillar arrangement ; in tlie Discomedusfe (Aurelia) it 

 contains a number of oval or stellate cells, and in the Cteuopbora there are 

 muscular stellate cells. In the Alcyonaria, cells lie imbedded in a gela- 

 tinous matrix and in them the calcareous spicules of the skeleton are 

 developed ; in the Actiniaria Madreporaria the lamina is fibrillar and con- 

 tains a few connective-tissue cells. Various arguments against its complete 

 homology with the mesoblast are advanced by the author. 



Arrang-ement of the Mesenteries in the parasitic larva of Halcampa 

 chrysanthellum (Peach).* — Prof. A. C. Haddon gives a bibliography of 

 all the Actinife known to occur as parasites on Medusae. It appears that 

 Halcampa fultoni is the larva of H. clirysanthellum (N. Europe) ; Philo- 

 medusa vogtii and H. medusophila are probably the yomig of Halcampella 

 endromitata (Mediterranean) ; Bicidium parasiticum is a Peachia (N.E. 

 America) ; lastly there are Hnlcampa clavm (Southern Ocean) and a 

 parasitic larval Edwardsia (N.E. America). A description of the larva 

 of H. chrysanthellum is given. Only eight tentacles are present. In the 

 oesophageal region the twelve mesenteries appear to have equal import- 

 ance. A deep siphonoglyphe is present which extends for a short distance 

 below the oesophagus. In the gastric region there are eight large mesen- 

 teries which alone bear the enlarged digestive borders ; the other four 

 mesenteries are shorter and have smaller muscular bands than the 

 former. Those four intra-mesent'^rial chambers, which are bounded by a 

 strong and a weak mesentery, are alone not prolonged into a tentacle. 

 The dorsal directive mesenteries also appear somewhat smaller than the 

 remaining six strong mesenteries. From the position of the muscular 

 band it is evident that the eight strong mesenteries of the larval Halcampa 

 are homologous with the eight mesenteries of Edwardsia and not with 

 the eight strong mesonteries of other larval Actinije. It is interesting to 

 note that no siphonoglyphe is noticeable in the adult, though it is very 

 conspicuous in the larva; and also that in the adult only six (lateral 

 and ventral) mesenteries bear generative organs ; these correspond to the 

 above-mentioned larval mesenteries. For the present we may assert that, 

 although the adult Halcampa closely resembles the ordinary Actiniae in 

 the ratio of its tentacles and the disposition of its mesenteries, the larval 

 form is undoubtedly more nearly allied to the Edwardsise, 



Porifera. 



Synocils, Sensory Organs of Sponges.f — Dr. R. v. Lendenfeld refers to 

 a remark made in this Journal on the occasion of our reporting bis account 



* Proc. R. Dublin Soc, v. (1887) pp. 473-81 (1 pi.), 

 t Zool. Anzeig., x. (1887) pp. 142-5. 



