150 Royal Society : — • 



homogeneous connective tissue, layers of connective-tissue cells, 

 and finely fibrous calciferous tissue. Prolongations of the two 

 former form sacs lining the ccenench^onal tubes and calicles. The 

 sacs are further lined by the entoderm, which consists of spherical 

 cells containing yellow pigment, as in other Alcyonarians. Only 

 a surface-layer in Heliopora is liATJig. Hardly any soft tissue is to 

 be found in the tubes beneath the last-formed tabula. The sacs 

 lining the tubes do not communicate anywhere directly with the 

 exterior, but are connected with one another above, and with the 

 calicular cavities, by wide transverse canals. The superficial tissues 

 are permeated by smaller canals. The polyps of Heliopora have 

 eight mesenteries and eight lobed tentacles. In the contracted 

 state of the polyp the tentacles are completely introverted, and 

 rest in the intermesenterial spaces. The stomach is like that of 

 any other Alcyonarian. Retractor muscles are present, which are 

 disposed with regard to the mesenterial plates as in Pennatulids, 

 showing a " Dorsalfach " and " Ventralfach." Xo definite pro- 

 tractor muscles were observed to be present. Xo regular arrange- 

 ment of the eight mesenteries with regard to the twelve so-called 

 septa could be found. Eight mesenterial filaments are present, 

 two of which appear to be longer than the others. In three 

 individuals only of the single colony examined were ova found — 

 in one four ova, in the others only one. The ova are attached 

 to the mesenteries. The four ova were attached to four separate 

 mesenteries. ]Vo male elements were found. The colonies are 

 probably unisexual. The arrangement of the poh'ps in the colony 

 is somewhat irregular ; but the " Dorsalfach " seems always to be 

 uppermost in the vertical plates of which the coral consists, the 

 polyps being thus placed back to back. 



On the Structure of Sarcophytou, sp. — An Alcyonarian was 

 obtained at the Admiralty Islands which agrees in every respect 

 with Lesson's genus Sarcojjhi/ton (M.-Edwards, Hist. IS^at. des 

 Corall. t. i. p. 22). A genus called Surcophyton is, however, cited 

 by Claus as having been formed by Sars. The Alcyonarian is 

 mushroom-shaped. Two kinds of indi\dduals, zooids and polyps, 

 compose the colony ; the stem is composed of large tubes 

 (" sinus"), the prolongations of polyp-cavities. The poh'ps offer 

 no marked peculiarities ; their retractor and protractor muscles are 

 arranged as in Pennatulids with regard to the mesenteries. They 

 have two mesenterial filaments longer than the rest. The zooids 

 have eight short mesenteries, four of which, the " dorsal " and 

 " ventral," are deeper than the rest. They have two mesenterial 

 filaments, the dorsal only. They have no tubercles and no genera- 

 tive organs. They have a simple globular stomach, communicating 

 by a short tube with the exterior, and Uned with long cilia. A 

 sarcosome of transparent homogeneous connective-tissue, con- 

 taining small ramified nucleate corpuscles, connects the polyp- 

 and zooid-carities ; these cavities are connected by vertical and 

 horizontal systems of canals. The vertical canals are continuous 

 with the bottoms of the zooid-cavities ; tbev form networks of 



