1907.] rnOM TUE CAPE VEKDE ISLANDS. [55] 



hyiliotheea, ami to these are attached strands su]5porting a flat- 

 tenetl disc-like portion at tlie base of the polyp. 8iich an attach- 

 ment, of course, makes the retraction of the polyp impossible. 

 The structure is identical with that whicli I liave already 

 described and figured in the genus Halecium (Ritchie, 1907, 

 p. 525), except that in Halecium the basal disc rests ujx)n the 

 perisarcal septum at the bottom of the cup, while liere a consider- 

 able .>ipace intervenes between the two, traversed by a narrow 

 strand of ccenosarc connecting the polyp with the common canio- 

 sarc of the colon}'. I would di-aw attention to the seeming 

 inaccuracy of Hincks's figures (1868, pi. 45. figs. 2, 2') as regards 

 the relations between polyp am! hydrotheca. The hydranths, 

 which are about 0'9 mm. in height, gi-adu;diy increase in diameter 

 upwards fi-om the basal disc, but exliibit no distill contniction 

 beneath the tentjicles sucli as Hincks figui-es. The bases of the 

 tentacles, which nundier about 23, are connected by a web witliin 

 which the liypostome arises. A secondary hydrotlieca, borne on 

 a relatively long peduncle, may arise from the lower portion of 

 the peduncle of a primarj" hydi-otheca. 



Xematophores occur frequently but ii-regularly. There is 

 usually one on a peduncle, and sometimes one on an inteniode. 

 They are sessile, cup-shaped, with delicate walls and everted 

 margin, within which there is commonly a row of refringent dots. 

 To the.se, as in the hydrothec*, a ba.sal ccenosarcal disc is attached. 

 The Siirco.styles con-espond to those figured by Hincks (1868, 

 pi. 45), with" thin walls bearing scjittered cnidoblasts, and a glo- 

 bular bead where large numbeis of these ofibnsive and defensive 

 cells are aggregated. When contracted, a sarcostyle measures 

 about 0-4 mm., wliile one which was extended measni-ed 2-0 mm. 

 The cnidoblasts are narrowly oval, 17^ by 3 fi, and each contains a 

 thread 220 fx long, armed near the base with a whorl of four barlis 

 in the form of a cross, distal to which are smaller liarbs pointing 

 towards the tip of tlie tln-ead an<l placed in four longitudinal 

 rows, each of which contains aljout nine gi-adually decre.nsing barbs 

 (Plate XXV. fig. 5). The cnidobla.sts occur throughout ahnost 

 the whole colony, but are particularly common on the basal discs 

 of sarcostyle and polyp, and at the tips of the sarcostyles and of the 

 tentacles. 



Occasionally soHt;iiy hydrotheca; and nematophores arise from 

 the hydroihi/^l tulie. 



The gono.some is not present. 



Locality. Porto Pniya, Santiago, 10 fathoms; 12th August, 

 1904. 



Family LafgEid.e. 



FiLELLUM SERPENS (Hassall 1852). 



Tliis species is represented by scanty specimens creeping on 

 a fragment of a Gymnoblast colony. In essential characteis the 

 specimens agree with Hincks's description (1868), but they appear 

 to be of less robu.st giowtli, while the margins of the hyibothecie 



501 



