'258 THE VOYAGE OF H.M.S. CHALLENGER. 



0"6 and 0'057, 0'35 and 0'058 mm. The tentacular portion is furnished with 

 numerous thin spindle-shaped spicules, which bear widely distant spinas, they measure 0'4 

 and 0-03 3 mm. in length and breadth. These form a collar around the base of the 

 tentacles, and longitudinal bundles of spindles are found extending into the apices of 

 the tentacles. The young polyps arise near the base of the old ones, which explains the 

 grouped arrangement of the polyps. 



The colour of the spirit specimens is a greyish-white. 



This species exhibits a close relationship with some of the northern forms, in which 

 the tentacles are usually strongly spicular, and the calyx wall is not very rigid, but beset 

 with large spiny spicules. 



It is most closely allied to Clavularia arctica, Koren and Dan., from which it is 

 however distinguished by the form of the spicules. 



Habitat.— ^ta.i\on 78, off the Azores, lat. 37° 26' N., long. 25" 13' W. ; depth, 1000 

 fathoms ; bottom, volcanic mud. 



Clavularia cylindvica, n. sp. (PI. XLIII. figs. 9, 10). 



The basal membrane forms a thick covering over the stem of a species of Dasygorgia. 

 The polyps arise from the whole surface vertically and at intervals of 1 to 2-5 mm. On 

 the apex of the colony they are more closely grouped together. In all cases the 

 retractile portion of each is completely withdrawn within the calyx. The calyces are 

 cylindrical, measuring 4 to 6 mm. in height, and on an average 2 mm. in diameter, but 

 slightly broadened at the base. The eight calycine ribs extend along the entire length, 

 and only become obliterated at the basis. The polyp walls are firm and do not collapse 

 when dried. In the ribs the spicules are disposed in thick longitudinal bundles. The 

 tentacles also contain numerous spicules. In the calyx these are in the form of thick 

 spindles, which are thickly covered with spiny warts. Their length and breadth vary, 

 and measure respectively 0-43 and 0-067, 0-3 and 0-04, O'lS and 005, O'lS and 0-03 mm. 

 The tentacles also contain spicules, which, converging towards the median longitudinal 

 axis of each, extend on to the apex. The tentacular spicules are blunt, spiny, straight 

 spindles, from 0-2 and 0-025 to 0-18 and 0-05 mm. in length and breadth. 



The species diverges somewhat from the other forms of Clavularia in this, that the 

 basal membrane is relatively thick, and forms a foundation for the lower portion of tlie 

 alimentary cavity of the polyps. From the embedded portion proceed four endodermic 

 stolons into the coenenchyma. The reproductive organs are found in the projecting 

 cylindrical portion of the polyps. 



The colour of the spirit specimen is a yellowish-white. 



Habitat. ~^is.t{on I35c, off Nightingale Island, Tristan da Cunha ; depth, 100 to 

 150 fathoms. 



