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



prominent, with numerous fusiform spicules, sometimes bent or twisted ; the base of the 

 tentacles furnished with a row of from six to eight long spine-like spicules ; tentacles 

 itnperfectly retractUe, with minute spicules. 



1. Acanella arhnscula (Johnston) (PI. IX. fig. 1). 



Mopsea arhuseulum, Yate Johnston, Proc. Zool. Soc. Lond., 1862, p. 245, pi. xxxi. figs. 1, la; 



Ann. and Mag. Nat. Hist., ser. 3, vol. xi. p. 299, April 1863. 

 Acanella arhnscula, Gray, Cat. Lithophytes Brit. Mus., 1870, p. 16 (woodcut). 



Several specimens of what we take to be this species were dredged off Station 3, 

 south of the Canaries. The axis is branched. The branches arising for the most part 

 in the one plane from the horny nodes ; two generally from the same node. The base is 

 pro%'ided with broad, calcareous, root-like processes, for anchoring in the mud. The 

 coeneuchyma is thin, with numerous fusiform spicules. The polyps show a tendency to 

 a uniserial arrangement. The polyps are almost sessile, with well-developed fusiform 

 spicules, some eight of which project and form a calyx around the base of the nearly 

 completely retractile tentacles. One specimen measures about 20 cm. in height, is more 

 or less fan-shaped, the broad expanse measuring about 15 cm. 



There is no trace of any anastomosing of the twigs, as mentioned by Yate Johnston to 

 be the case in the specimen described by him. The species seem very closely related to 

 Acanella normani, VerriU {Acanella arhnscula, Norman), but the spicules do not appear 

 to be " minutely spinulate " as described by Verrill. 



The colour in spirit is a dull brown, but the tentacles are of a much darker hue, and 

 when withdrawn give the appearance of black tips to the polyps. The spicules on the 

 outside of the polyps, and those forming the calycine fringe, measure 3'6-0*l ; 3-0'09 ; 

 2-0 '05 mm. The smaller forms in the coenench}Tiia and tentacles measure from 0"13- 

 0-02 ; 0-3-0-05 ; 0-6-0-03 mm. 



Habitat. — Station 3, south-west of the Canaries; depth, 1525 fathoms; bottom, 

 hard ground. 



2. Acanella eburnea (Pourtales) (PI. IX. fig. 2). 



Mopsea eburnea, Pourtalfes, Bull. Mus. Comp. ZooL, vol. i. p. 132, 1868. 

 Isidella eburnea. Gray, Cat. Lithophytes Brit. Mus., 1870, p. 15. 

 Acanella eburnea, Verrill, loc. cit., vol. xL p. 16, 1883. 



A much-rubbed specimen of this species occurs in a collection made off" Sombrero 

 Island. The coenenchyma on the axis is thin. The echinulate spicules seem very 

 characteristic of the species. This may be Acanella spiculosa, Verrill (loc. cit., p. 17), 

 but contrary to his usual habit, Verrill gives no measurements of the spicules of this 

 species or of Acanella eburnea, though he makes the specific differences depend in some 

 measure on their relative size. 



