PROF. THOMSON AKD MR. McQUEEX — REPORT ON TflE ALCYONARIANS. 91 



111 the living colonies there was considerable difiference in coloration : — 

 (a) whitish stems, bluish tentacles, grey pinnules ; (6) whitish-ljrown 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 ajipoar as if they only had one row. It was easy to find tentacles 

 with throe rows of 20 pinnules, or two rows of 30 pinnules. This matter of 

 rows of pinnules is a 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 

 >ize 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 HO 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.— Yariom parts of Siiakim Harbour, 1-2 fathoms. Previously 

 recorded from Red Sea, Mozambiq^ue, Tumbatu, Zanzibar, Ceylon, Paciiic 

 Ocean (New Britain). 



Xe\IA c.erulea, Ehrenherg. 



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 zoochlorella?- 

 I n some cases the colour remained bright green. Under low power the surface 

 liad a glistening appearance, as i£ dusted with refractive particles. These are 

 /.ooeh'orellse, not spicules. The calcareous corpuscles are very minute and by 

 no means abundant. The siiecimen may be referred to Ehrenberg'.s X. cwrulea, 

 or, what comes almost to the same thing, it may be regarded as a dwarf 

 variety of A'. umbeUata *. In another specimen the number of pinnules on 

 each side was 2-4 in two rows, tlie whole surface glistened with zoochlorelly, 

 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. Etuleh shoals in Suez Bay. 



• It seems certain tlint A'. timMlata, Liinmrck, X.fuscescem, Ehrenberg, and X. c<Bru!ea 

 l',hrenberg, are very closely related. It may be necessary eventually to unite them in ouc 

 variable species. 



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