REPORT ON CORALS — HELIOPORID^E. 117 



found for examination having been disappointed. In Plate I. fig. 1 the mesenterial 

 filament is, in the drawing, stopped short above the ovum in order to allow the ovum to 

 be seen. The filaments belonging to the septa bearing ova hang down below the ova. 

 No trace of any male elements was found in any polyp. The colonies of Heliopora are 

 probably unisexual. 



Disposition of the Dorsal and Ventral Aspects of the Polyps. — The investigation of 

 the positions of the dorsal and ventral aspects of the polyps in the Hdiopora colony rela- 

 tively to the axes of growth is extremely difficult, because, when a horizontal section is 

 cut sufficiently deep down to display the muscular arrangement, nothing remains to hold 

 the various sections of polyps in position but the imbedding substance made use of ; and 

 where the only substance at command, as in the present case, was wax, the sections with 

 the wax unremoved were found almost too opacpie and indistinct for observation. By 

 examining such sections, held together by the wax and made transparent with glycerine, 

 I have found that the polyps (although they are often turned oil their central axes to a 

 considerable extent, so that the long axes of their stomachs are not by any means parallel, 

 but often inclined to one another at very considerable angles) have nevertheless their 

 dorsal surfaces, or the intermesenterial spaces devoid of retractor muscles (" Dorsalfacher"), 

 always nearer to the summits of the colony than are the "Ventralfacher." The " Dorsal- 

 facher" thus show a general tendency to take a superior position, i.e., lie uppermost, in the 

 vertical plates of which the colony is composed. The entire coral makes up a flat plate, 

 with two outer surfaces, towards which the polyp-tubes are directed in curves on either 

 hand from the vertical axis of growth ; and the polyps thus curving away from one 

 another have their "Dorsalfacher" approximated, or may be said to be placed back to 

 back. 



On the structure of a species of Sarcophyton. 



An Alcyonarian dredged in shallow water amongst the reefs on the shores of the 

 Admiralty Islands was examined in order to compare its structure with that of 

 Hcliopora. The Alcyonarian in question appears to belong to the genus Sarcophyton, 

 Lesson, 1 originally described in the Zoologie du Voyage de la Cocpiille, and possibly to 

 his species lobatum. 2 The genus is stated by Milne-Edwards to be imperfectly known. 

 The specimens correspond in every particular with the description as given by Milne- 

 Edwards. The Alcyonarian has exactly the form of a mushroom, with a cylindrical stem 

 and polyps confined to the upper surface of the pileus. Many specimens were obtained, 

 but unfortunately only one was retained for dissection during the voyage, the remainder 

 packed away. 



1 Milne-Edwards and Haime, Hist. Nat. des Coralliaires, torn. i. p. 122. - Zooph., p. 92, 1831. 



