PROF. THOMSON AND MR. McQUEEN—REPORT ON THE ALCYONARIANS. 51 
In the living colonies there was considerable difference in coloration :— 
(a) whitish stems, bluish tentacles, grey pinnules ; (b) whitish-brown stems, 
chocolate-brown polyps ; (¢c) whitish zooids, chocolate-brown tentacles. 
Some of the colonies which seem referable to this variable species show 
only two rows of pinnules on each side of the tentacles, and greatly elongated 
tentacles appear as if they only had one row. It was easy to find tentacles 
with three rows of 20 pinnules, or two rows of 30 pinnules. This matter of 
rows of pinnules isa very untrustworthy and useless character. Young polyps 
occur at the bases of those fully-formed, and show various stages from 
minute zooid-like buds on which no tentacles are visible with low power, to 
small forms with distinct tentacles and pinnules, but only about a tenth the 
size of the ordinary polyps. Over and over again we have thought for a 
time that we had to do with a clear case of dimorphism of zooids, but further 
examination has shown that there: were transitions between minute polyps 
showing no tentacles and others not much larger which exhibited them. 
Moreover, in colonies apparently identical in every other respect with those 
showing minute zooids without tentacles, no such zooids could be found. 
Localities—Various parts of Suakim Harbour, 1-2 fathoms. Previously 
recorded from Red Sea, Mozambique, Tumbatu, Zanzibar, Ceylon, Pacific 
Ocean (New Britain). 
XENIA CHRULEA, Mhrenberg. 
A small specimen growing on a coral fragment presents some difficulty. 
The polyps are about 3°5 mm. in height, the tentacles are about the same. 
On each side of the tentacle there are 16-20 pinnules, in 2—3 rows or in one. 
The two lowest pinnules are small, but it cannot be said that there are 
two kinds of pinnules. The extended pinnules are elongated, slender, and 
pointed. 
The tentacles and the bodies of the polyps show large numbers of zoochlorelle. 
In some cases the colour remained bright green. Under low power the surface 
had a glistening appearance, as if dusted with refractive particles. These are 
zoochlorellee, not spicules. The calcareous corpuscles are very minute and by 
no meansabundant. The specimen may be referred to Hhrenberg’s_X. cwrulea, 
or, what comes almost to the same thing, it may be regarded as a dwarf 
variety of X. umbellata*. In another specimen the number of pinnules on 
each side was 24 in two rows, the whole surface glistened with zoochlorelle, 
and no effervescence was seen when the polyp was placed in dilute acid. 
Locality.—Off S.E. corner of Shubuk, 9 fathoms ; bottom of coarse sand, 
shells, and coral. Htuleh shoals in Suez Bay. 
* Tt seems certain that X. wnbellata, Lamarck, X. fuscescens, Ehrenberg, and -X. cerulea 
Ehrenberg, are very closely related. It may be necessary eventually to unite them in one 
variable species, 
