156 Boyal Society/ : — 



occurrence in them, alone of all Anthozoa, of intracalicinal gem- 

 mation *. 



With regard to Sarcojyhi/ton, the fact that compound colonies 

 composed of niultitudes of zooids, combined with a lesser number 

 of sexual polyps, occur amongst the Alcyonidae, as well as amongst 

 the Pennatulidae, in which they are so well known from Kolliker's 

 great work, appears to be new to science. That in such colonies 

 and in Heliopora the " Dorsalf acher " are all turned towards the 

 axis of the colony and directed upwards is also a new fact. The 

 zooids in their structure seem to conform very closely to those of 

 Pennatulids {Sarcopliyllum, e. g.) ; but to the list of distinctive 

 differences between the zooids and polyps of Pennatulids given 

 by Kolliker, viz. the absence in the zooids of tentacles, the 

 presence of two mesenterial filaments (the dorsal ones), the ab- 

 sence of generative organs, and the shortening of the hypogastric 

 region to such an extent that it fuses with the anastomosing 

 canal-system — to these marks of distinction must be added, in the 

 case of the zooids of Sarcophyton, the fact that four of the 

 mesenteries, the dorsal and ventral pairs, are deeper than the 

 others. 



It seems extremely difficult to reconcile the extraordinary 

 succession of the mesenteries in the development of the Zoan- 

 tharians, discovered by Lacaze-Duthiers, with the facts presented 

 by Alcyonarians. Did the development of the eight mesenteries 

 of Alcyonaria correspond with that of the first eight mesenteries 

 formed in Actiniadfe, the first mesenteries formed would be either 

 the lateral dorsal or lateral ventral ; but these are those which are 

 most rudimentary in the zooids of Sarcophyton. Moreover the 

 mesenterial filaments of the two lateral pairs of septa are in the 

 development of Actiniadae the first to appear, and not the dorsal, 

 which are longest in the Alcyonarian polyps and most persistent 

 in the zooids. Apparently, however, development in Alcyonarians 

 follows a different course. 



In Halysceptrum, the development of which has been examined 

 by Kolliker, the eight mesenteries appear from the very first. In 

 Kalliphohe (Busch), one of the Edwardsice, according to Metschni- 

 koff, the larva has, in its earliest stage, eight tentacles and two 

 mesenterial filaments. 



The peculiarities presented by the Stylasteridae have struck 

 many observers. M.-Edwards and Haime placed these corals 

 (Stylasteracea) under the Oculinidae. Gray, however, established a 

 family (Stylasteridae) for the genus St ylaster alone. Pourtales, who 

 in his 'Deep-Sea Corals' dwells upon the many peculiarities of the 

 corallum of this family, places under it the genera Allopora, Sty- 

 laster, IJlst'u-hopora, C'ryptoheliaf, Lepidopora, and Errina. The 



* An examination of the Cornulariadte, tbe only recent solitary Alcyonarians, 

 might, very possibly throw light on the question of the affinities of the Rugosa. 



t Pourtales has remarked that the genus Endohelia of M.-Edwards and 

 Haime appears undistinguishable from the genus Cr^ptokehaoi the Ba,me&\ithoTS. 

 Ejidohelia is founded un a Japanese species. The 'Challenger' dredged a coral 

 certainly not generically distinguishable from Cryptohelia off the coast of Japaa. 



