270 CEYLON PEARL OYSTER REPORT. 



is "littoral" in the wide sense, but it may be noted that the explorations of the 

 " Investigator" show that the deep water off Ceylon is also very rich in Alcyonarians. 

 In reporting on Professor Herdman's collection, we have had to deal with at least 

 75 species, representing at least 40 genera. About 32 of the species seem to us to be 

 new, and the number might have been considerably increased if we had exercised less 

 restraint. Our restraint in multiplying species has been mainly due to the ignorance 

 that obtains in regard to the internal structure of many Alcyonarian types an 

 ignorance that cannot be removed without specimens specially preserved for histo- 

 logical purposes. Wonderfully diagnostic as spicules often are, they have been used 

 too confidently and liberally in the establishment not only of species, but of genera, 

 and a secure natural classification of Alcyonarians is still far to seek. Moreover, in 

 some of the forms which we have studied, e.g., Spongodes, there is great specific 

 variability both as regards spiculation and branching. As an astounding illustration 

 of diversity of spiculation in a single species, we may refer to our description of the 

 form which we have called Echinogorgia multispinosa, n. sp. 



Before proceeding to the systematic report, we may call attention to a few 

 facts of general interest : 



(a) Very striking is the frequent illustration of " convergence," i.e., the occurrence 

 of superficially similar forms which are not in reality nearly related. Thus, on one 

 occasion, three similar bright red forms were collected in one haul and loosely bound 

 together with thread. An examination of this small parcel disclosed three species 

 belonging to separate genera Keroeides gracilis, Verrucella rubra, n. sp., and Telesto 

 rubra. Equally marked is the resemblance between Echinomuricea indo-malaccensis, 

 Ridley, and Echinogorgia pseudosasappo, Kolliker, to which Ridley calls attention 

 (1883, p. 235), and many other examples might be given. 



(b) We have compared the Ceylon collection with two others entrusted to us, one 

 made in the Indian Ocean by Major A. Alcock, F.R.S., the other made at Zanzibar by 

 Mr. Cyril Crossland, M.A., and we find that the three collections have extremely 

 little in common. This is mainly because Alcock's collection was from deep water, 

 and Crossland's chiefly from close in-shore, but it may also indicate that many 

 Alcyonarians have a restricted local distribution. There is also a great difference 

 between the collection here discussed and those made off the Maldives by 

 Mr. Gardiner, and off New Britain, New Guinea, &c, by Dr. Willey. It may be 

 of interest to note that three Alcyonarians brought from Patani (Siam) by Mr. Nelson 

 Annandale and Mr. H. C. Robinson are unrepresented in Herdman's collection 

 (though included in this report), viz., Telesto trichostemma, Astromuricea rdmosa, n. sp., 

 and Juncella trilineata, n. sp. 



(<) Some of the distributional facts, on the other hand, point in a different 

 direction, showing that species occur in Ceylonese waters which enjoy a wide range 

 elsewhere. Thus the exceedingly beautiful Primnoa ellisii is known from the 



