6 THE VOYAGE OF H.M.S. CHALLENGER. 



liard, white, calcareous base is strongly contrasted with the axis of the stem. The calicles 

 are prominent, scattered along the branches, either standing at right angles or obliquely ; 

 they are covered with moderately large, elongated or flat spicula, and ai-e usually 

 eight-lobed at the summit. Ccenenchyma very thin, with oblong or elongated spicula." 



With our knowledge of the simple, unbranched form of Stroplwgorgia, which in the 

 structure of its polyps and the formation of its axis and spicules shows so near a 

 relationship to Dasygorgia, it seems well to unite these in one family, Dasygorgidse, 

 making Verrill's family of the Chrysogorgidse a subfamily, for which the family characters 

 laid down by him still hold good. 



With regard to the relationship of the ChrysogorginsB to other Gorgonids, Verrill has 

 pointed out their close connection with Isidse and Primnoidse. The relationship to the 

 Isida3 is strengthened by the examination of the new genus Primnoisis, which in the 

 structure of the polyps stands very close to the scaly forms of Dasygorgia. To the 

 Chrysogoi'gina3 must also be referred the genus Riisea, Duch. and Mich., which, as 

 regards branching and structure of the polyps, unites itself with this family. 



[Genus 1. Iridogorgia, Verrill. 

 Iridogorgia, Verrill, Bull. Mus. Comp. Zool., vol. xi. No. 1, pp. 21, 26, 1883. 

 With a spii'al axis, from which a single series of long, slender, simple branches is given 

 off on the outer side so that they likewise have a spiral arrangement. Zooids as well as 

 polyps are present. 



Iridogorgia pourtalesii, Verrill. 



Iridogorgia pourtalesii, Verrill, loc. cit., p. 27. 

 Hahitat. — Ofi" Dominica; depth, 542 fathoms. 

 Off Guadeloupe ; depth, 743 fathoms.] 



Genus 2. Dasygorgia, Verrill {emend.). 

 Dasijgm-gia, Verrill, Bull. Mus. Comp. Zobl., vol. xi. No. 1, p. 21, 1883. 



Colony branched, consisting of a main stem and branches, which again give off twigs, 

 and, indeed, follow the ty]^)e of the uniparous cyme. The ccenenchyma is thin, with two 

 layers of calcareous spicules. The poh^j^s are large, mostly projecting perj)endicularly 

 from the twigs, and arising at wide intervals. There are seldom more than two on a 

 node. The last polyp is never placed terminally, the ccenenchyma and axis are always 

 produced beyond its base. 



The spicules always form several layers upon the stem and polyps, and are produced 

 along the dorsal sides of the tentacles, but are wanting in the pinnules. They form an 



