STRUCTURE AND RELATIONS OE CERTAIN CORALS. 
109 
On the Structure of Sarcophyton, sp. 
An Alcyonarian dredged in shallow water amongst the reefs on the shores of the 
Admiralty Islands was examined in order to compare its structures with those of 
Heliopora. The Alcyonarian in question appears to belong to the genus Sarcophyton 
(Lesson) M.-Edwards and Haime (‘ Hist. Nat. des Coralliaires,’ t. i. p. 122), originally 
described in the ‘Zoologie du Voyage de la Coquille,’ Zooph. p. 92(1831). The genus 
is stated by M.-Edwards to be imperfectly known. The specimens correspond in every 
particular with the description as given by M.-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 
retained for dissection, the remainder being packed away. 
In this specimen the pileus is about 5 centims. in diameter, being somewhat oval in 
outline ; the height from the bottom of the stem to the summit of the pileus is also 
about 5 centims. ; the diameter is about 1*5 centim. The colony is of a uniform 
brown colour. 
By Claus {l. c. p. 208) a genus of the Alcyoninee, called also Sarcophyton , is given 
as founded by Sars. I do not know whether the old genus Sarcophyton has been 
abandoned and the name used again, or whether there is some error here. The form 
now under consideration certainly belongs to Lesson’s genus, and possibly to the 
species lobatum. On examination the Sarcophyton was found to present many points 
of interest, especially in comparison with Heliopora ; a short description of its anatomy 
will therefore be given. 
As in Pennatulids two kinds of individuals, sexual and asexual, polyps and zooids, 
compose the Sarcophyton colony. The stem of Sarcophyton consists of a series of 
tubular canals running parallel to one another vertically, and bound together by 
abundant transparent connective-tissue, in which are closely packed, numerous, stout, 
calcareous spicules of the common elongate cylindrical form, pointed at both ends, and 
covered with small lateral tubercles. The canals are prolongations of the polyp-cavities 
from above. The surface of the stem and under surface of the pileus are covered with 
an even coat of epidermis, and entirely free from polyps or zooids. On the upper 
aspect of the pileus the surface is covered all over with polyps or zooids. Over the 
general upper surface the polyps are pretty evenly distributed at intervals, the inter- 
spaces being filled by numerous zooids ; but at the margin of the pileus, where its 
edge is turned down and slightly recurved, is a narrow zone all round, occupied 
by thickly set polyps with very few zooids. In a vertical section through the central 
axis of the whole colony, the polyp-tubes are seen to be arranged with great regu- 
larity, converging in curved or vertical lines, according to position, towards the stem. 
The circular areas occupied by the retracted polyps measure L4 millim. in diameter, 
those occupied by the zooids *42 millim. in diameter — the difference in dimensions being 
here much less than in deeper regions of the colony, where the polyp-cavities widen 
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