94 CEYLON PEAEL OYSTER REPORT. 



Before proceeding to the systematic report, we would make a few general 

 observations : 



(a) In the detailed classification of Antipatharia much importance has been 

 attached to the form and distribution of the spines on the axis. But it does not 

 seem to have been sufficiently emphasised that there is considerable variation in both 

 of these characters in the different parts of the colony. Thus in the branched forms the 

 nature of the spines, the number seen from one aspect, and the arrangement of these 

 in spirals or longitudinal rows in no way correspond on the larger branches and on 

 the pinnules (Plate, fig. 2). In the simple colonies this is even more emphasised, e.g., 

 in Cirripathes {?) (Plate, fig. 8) those at the base are arranged irregularly (a), those 

 about the middle of the colony have a distinct linear arrangement (6), while those 

 near the tip are disposed in whorls around the stem (c). This distinction has been 

 illustrated relative to the species described, in the figures on the Plate, where two 

 views, and in one case three, have been given. This is of great importance where 

 species are determined from fragmentary specimens. 



(b) This difference between stem, branches, and pinnules is also borne out with 

 regard to the size and shape of the polyps. In many of the specimens, on the stem 

 and larger branches, the polyps are almost circular and disposed irregularly, their 

 diameter being less than that of the axis, while on the pinnules they are elongated 

 and rectangular, exceeding in breadth the diameter of the axis. Their distribution 

 also varies in the different portions of the colony ; they are often separated by 

 considerable intervals on the older parts, while on the pinnules they may be closely 

 apposed. The length and degree of transparency of the tentacles does not seem to 

 be a safe criterion, varying as it does with the degree of contraction and the mode of 

 preservation. 



(c) Of some general interest and deserving further investigation is the extra- 

 ordinary modification shown in the spines of several species. The general Anti- 

 patharian spine is simple or papillose, but in some species they pass from an 

 elongated sinuous form through a series of gradations to an antler-like growth and 

 eventually simulate a tree-like structure (Plate, fig. 1, a-f). This has been 

 previously noted, e.g., by Carter for Antipathes spinosa (Carter), but no inter- 

 pretation has been suggested. It may be due to a pathological condition, and in 

 some cases where branched spines were observed it was noted that a sponge-like 

 growth surrounded the axis, or it may be the result of irregular regeneration of 

 broken spines. It is particularly well seen at the base of Antipaihes gracilis, n. sp., 

 and on Antipathella rugosa, n. sp. In Antipathes abies, Gray, a forking of the spines 

 was occasionally observed. 



(d) The polyps of Antipathes abies, Gray, which were unknown when Mr. George 

 Brook described the " Challenger " Antipatharia, are very well preserved in some of 

 Herdman's specimens, and we have therefore given a full descrij^tion and figures of 

 their external features (Plate, fig. 4). 



