REPORT OK THE ALCYONARIA. 49 



orbicular in form ; they are finely serrated on their edges, and are tuberculated all over ; 

 the tubercles radiating from a nucleus, which is either central or excentric ; they are 

 large, those of the body measuring 1 to 1 by 0'80 by 0"75 mm. The row of subcalycine 

 spicules are triangular in shape ; the apices prolonged into long spines ; some of the 

 largest measure 1-0 "5 mm. across the base, with 1 mm. in length to base of spine ; the 

 total length including the spine varies from 4 to 4 "5 mm. The triangular portions are 

 tuberculated as in the other spicules, but the spines are smooth, circular on section, and 

 hollow. The opercular scales are of an isosceles-triangle shape, more serrated at the base 

 than on the longer sides ; sometimes winged, measuring r50-l*75 ; 1-1 '50 mm. 



It seems probable that this species lived prostrate in the mud, and possibly there 

 may have been some power of exjjansion and contraction in the colony. It is evidently 

 closely related to Primnoa. It was dredged in the most southern station reached by the 

 Challenger. 



Habitat. — Station 153, near the Antarctic Sea (the most southerly dredging during 

 the cruise) ; depth, 1675 fathoms ; bottom, blue mud. 



Subfamily 2. Calyptrophorik^. 



In 1870 Dr. Gray* established a family " Calyptrophoridse " for his genus Calyjitro- 

 phora. While there can be no doubt as to the form for which the family and genus 

 were intended, it would be impossible to identify the species from the diagnosis of either. 

 In several respects Calyptrophora is related to such genera of the next subfamily as 

 Calypterinus, Stachyodes, &c. The very remarkable annular form assumed by some of 

 the spicules of the bodies of the polyps will, however, with certainty distinguish it ; indeed 

 the presence of these scales with their broad and deep dorsal surfaces, and their equally 

 broad but narrow ventral surfaces, will mark out the species of this genus from all other 

 Primnoids. 



The colony is branched in the one plane. The axis is hard, calcareous. 



Polyps in whorls. The coenenchyma of the axis is thin, with large irregularly shaped 

 calcareous spicules, slightly overlapping. The second and third series of spicules on the 

 bodies of the polyps are annular. The dorsal portions (mandral) of each are broadly 

 expanded, forming a protective and defensive covering to the polyp. The tentacles are 

 retractile, and the opercular scales are well marked. 



' Cat. Lithophytes Brit. Mus., p. 41. 



(ZOOL. CHALL. EXP. — PART LXIV. — 1887.) ' Sss 7 



