972 SUMMARY OF CURRENT RESEARCHES RELATING TO 



functions by six mesenteries is not so well marked ; the polyps are monoe- 

 cious. 



In a concluding note, Dr. Fowler points out the logical fallacy of 

 Dr. Koch^s argument that the skeleton of Flabellum is an epitheca, and 

 urges that there is nothing in the structure of its corallum which is really 

 inconsistent with the idea that it is a theca. 



Anatomy of Mussa and Euphyllia, and the Morphology of the 

 Madreporarian Skeleton.* — Mr. Gr. C. Bourne gives an account of the 

 anatomy of Mussa and Euphyllia, two genera of Madreporaria aporosa. In 

 the former the soft tissues of the polyp extend downwards for a consider- 

 able distance on the outside of the corallum ; so that there is a well- 

 developed " Eandplatte," and this contains extrathecal continuations of the 

 exocoeles and entocoeles. The only point of divergence from the normal 

 actinian type is the absence of directive mesenteries ; this is the case also 

 with Euphyllia and with Lophohelia (see Fowler, supra'). The calicoblasts 

 are either rounded or polygonal, or are drawn out into very long, narrow, 

 columnar cells ; the pyramidal or oval cells, which have been regarded by 

 Sclater and v. Heider as calicoblasts, are always associated with the 

 mesogloea of the mesenteries, and are, as Fowler suggests, connected rather 

 with the attachment of the mesentery to the corallum than, with the secre- 

 tion of coral. Mussa, EupJielia, and Lophohelia show no indication of 

 bilateral symmetry, but are perfectly radial ; this may be a primitive con- 

 dition or may be connected with fissiparity. In Euphyllia the stomodoeum 

 is very long, and is converted into a ramifying and inosculating system of 

 canals; the endoderm is greatly vacuolated, and becomes a reticulated 

 tissue filling up the coelenteron, in the meshes of which are numerous 

 nematocysts and symbiotic algse. In the stomodoeal canals there are nume- 

 rous fragments of vegetable matter ; this observation is of interest, as it 

 seems to be the first instance recorded of a coral feeding on a vegetable 

 diet, and also as proving the digestive function of the enormously and 

 peculiarly developed stomodoeum. 



The author suggests the following as the best provisional arrangement 

 of the Madreporaria : — 



I. M. with no directive mesenteries and a perfectly radial symmetry — 

 Lophohelia, Mussa, and Euphyllia. 

 II. M. with directive mesenteries and a combined radial and bilateral 



symmetry — Turhinaria, Bhodopsammia, Fungia, &c. 

 III. M. with reduced radial symmetry and marked bilateral arrange- 

 ment of parts — Madrepora, Pocillopora, Seriatopora. 

 TV. M. with a basal pseudocheca and no " Eandplatte " — Flabellum. 



The Madreporaria differ from the Alcyonaria in that the calcareous 

 tissue is always external to the polyp ; in the latter ectodermic cells become 

 imbedded in the mesogloea and there develope spicules. 



Porifera. 



Cladorhiza pentacrinus.f — Mr. A. Dendy describes a very remarkable 

 Monaxonid sponge, which has a curious external resemblance to the 

 pentacrinoid larva of Antedon. The sponge has a long slender stem, which 

 terminates above in a subglobular body bearing a circlet of short pinnae or 



* Quart. Journ. Mier. Sc-i., xxviii. (1887) pp. 21-51 (2 pis.), 

 t Ann. and Mag. Nat. Hist., xx. (1887) pp. 279-82 (1 pL). 



