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



Suheiites ranndostis, Y£iT. cylindrifeo-a^ (PI. XXIX. figs. 5, 5a; PI. XLIII. figs.' 13, 14). 



1886. Suheriies ramulosa, var. cylindrifera, Kidley and Dendy, Ann. and Mag. Nat.' Hist., ser. 5, 



vol. xviii. p. 487. 



Sponge (PI. XLIII. figs. 13, 14) consisting of one or more heads, with long, slender, 

 simple or branched stalks ; when the stalk is simple there is only one head, but when it is 

 branched there is a head at the end of each branch. The stalk is slender, usually more 

 or less crooked, and ends below (in perfect specunens) in branching rootlets ; at its 

 upper end it gradually expands into the elongated, pear-shaped head, which terminates in 

 a single osculum at the summit. When the stem is branched the branches come ofi" from 

 the main stem at various angles and quite irregularly ; when a stem comes into contact 

 with a head or with another stem the parts in contact may anastomose. Size of specimens 

 variable; the finest unbranched specimen has a head which is 31 mm. long by about 

 13 mm. broad, and a stem about 100 mm. long by about 2*5 mm. thick. Colour in 

 spirit dirty, greyish-yellow. Texture of head rather soft and spongy ; of stem firm 

 and fibrous. Surface strongly hispid. Oscula ; normally there is a single one, sur- 

 rounded by a slight spicular fringe, at the summit of each head. 



Skeleton. — The skeleton of the stem consists of a dense, central axis of large, blunted 

 stylote spicules, from which project at right angles loose tufts of smaller, subtylostylote 

 spicules whose points project beyond the surface. That of the head consists of ascending 

 lines of very loose spiculo-fibre, composed of the large, blunted styli, running very 

 ol)liquely to the surface, where they end in loose, irregular tufts of smaller subtylostyli 

 whose points project outwards and upwards and give to the surface its uniform hispidity. 



Spicules. — Megasclera; (l)long, smooth, straight, slightly fusiform (cylindrical) styli 

 (PI. XXIX. figs. 5, 5a), evenly rounded off at the base and tapering gradually to a narrow, 

 but rounded, apex; size about 2*6 by 0"056 mm. (2) Long, straight or sHghtly curved 

 subtylostyli, with slightly developed heads and usually sharply pointed at the apex ; size 

 very variable, passing by occasional transitional forms into the larger spicules, commonly 

 measuring about 1"0 by 0'014 mm. but often smaller. 



This very interesting variety is well represented in the collection Ijy a large number 

 of fiine specimens ; indeed it is very much better represented than the more typical form of 

 the species. A very remarkable point in connection with it is the high temperature 

 (71°"0) of the water in which it grew ; it was obtained from Station 209 only, while the 

 types of the species were obtained from Station 207. It differs from the types mainly in 

 the absence of heads to the larger megasclera and in their still greater bluntness, 

 and throws considerable doubt on the specific value of these characters ; diflerences also 

 exist in the proportions of the spicules, which will be seen by comparison of the descriptions. 

 As regards external form there is very little difference to note between the specimens 



' So-called on account of the strong tendency exhibited by the larger spicules to become cylindrical. 



