EEPOKT ON THE A LC YON ARIA. 105 



\ Genus 4. Muriceides, n. gen. 



In this genus the colony is erect, slightly branched, with a thin cocuenchyma on 

 which the large upright polyps rise at considerable intervals ; the basal portion of their 

 tentacular coronet is armed with strong spicules, and when in repose it is folded fi-om 

 about midway over the oral disc, its base forming a somewhat lofty operculum. There 

 is also a ring-shaped colleret of spicules. The calycine spicules are ii-regularly placed, 

 and here, as in tlie coenenchyma, their terminal points project often as short rough 

 needles. 



The axis is horny and flexible. The only species at present known has a bifurcate 

 stem, which arises from a flat basal expansion, growing on foreign bodies. It divides 

 speedily into two forked branches, which are thickened at the apices into club-like 

 forms. The coenenchyma is thin and prickly, the latter owing to the numerous pro- 

 jecting points of the spicules. 



The polyps stand at long intervals from one another ; they are longer than 

 broad, cylindi'ical, or bluntly conical, and with an elevated tentacular operculum, 

 which seems to spring from the colleret. The spicules are in part spiny, in part flat, 

 and often branched ; " Stachelplatten " are also met with, with one termination pointed 

 and the other broad, and wdth two or three spiny prominences. There are also curved 

 spicules, wdth spiny and often branched prominences on their curvatures. 



This genus comes between Paramuricea and Clematissa. The form of its spicules 

 corresponds to that of those of Paramuricea, while the irregular arrangement of these 

 on the wall of the polyps corresponds to that met with in Clematissa. 



Muriceides fragilis, n. sp. (PI. XXII. fig. 5 ; PI. XXV. fig. 1). 



In this species the short stem arises from a flat expansion of the basal portion, with 

 a diameter of 1 mm. ; at an elevation of 64 mm. it gives off a lateral twig, which is as 

 thick as the main axis and is 80 mm. long ; at its apex it is a little thickened. The 

 coenenchyma is rough, thin, though not transparent. The cylindrical, elongated polyps 

 arise from the basal portion of the stem in isolated patches, and for an extent of about 

 1 1 mm. polyps are found ; on the rest of the stem they are very few in number ; they 

 are in greater numbers on the branches, though even here at long inters'als, and ai-isiug 

 chiefly from one side. 



The terminal portion of the branch is occupied by three polyps rising in same plane ; 

 none of which however form the apex. The calyces arise perpendicularly from the 

 stem and branches ; they are cylindrical or bluntly conical, 2 to 3 mm. high, with a 

 diameter at the basal portion of 2 mm. 



The tentacular operculum, which is 1'5 mm. high, is placed on a colleret of spicules. 



(ZOOL. CUALL. EXP. — PART LXIV. — 1887.) SsS 14 



