REPORT ON THE MONAXONIDA. I S3 



Off Tristan da Cunha, October 18, 1873 ; depth, 100 fathoms. One specimen. 



Off Nightingale Island, Tristan da Cunha; depth, 100 to 150 fathoms. Two specimens, 

 and also a third, which, though it differs rather strikingly in external form from the rest, 

 we have decided to include in this species pending further discoveries. The specimen in 

 question is erect, clathrous, and proliferously branched ; the branches are very short and 

 compressed (PI. XXXV. fig. 1). 



Habitat. — ? British Isles (Bowerbank); Atlantic Ocean, between the North of Scotland, 

 the Shetland and the Faroe Islands (Carter) ; South Atlantic and Southern Ocean 

 (Challenger). 



Axinella echidnxa, Ridley, var. n. (PI. XXXVI. fig. 3). 



1813. (?) Spongia echidnxa, Lamarck, Ann. Mus. Hist. Nat., vol. xx. p. 448. 



1884. Axinella echidnsM,'R\dL\(ij, Zool. Coll. H.M.S. " Alert," Brit. Mus., p. 462, pL xliii. He;, a. 



There occurs in the collection a single specimen (PL XXXVI. fig. 3), from off Bahia, 

 which we propose to consider as a variety of the above-mentioned species. The various 

 points in which it deviates from the type of the species may be briefly enumerated as 

 follows: — (l) External appearance; the type specimens have, for the most part, a 

 broadly flabellate form, while the Challenger specimen, consisting, however, of only a 

 single branch, is (like one of the types) cylindrical, and its surface is beset with numerous 

 irregular prominences ; these prominences are much larger, broader and further apart 

 than in the tyj^e. (2) Spiculation ; the spicules are, as in the type, smooth 

 oxea and styli, the former being much more abundant than the latter. In the present 

 variety the oxeote spicule measures about 0'5 by 0'022 mm. and the stylus about the 

 same. For the type, however, the spiculation is given as follows: — " (l) Smooth, slightly 

 curved acerate, tapering gradually to sharp points, or more or less blunted at one or 

 both ends; size "3 by "0095 to "44 by '0127 millim. : these forms compose the main 

 bulk of the skeleton. (2) Long smooth acuate, generally slightly curved, tapering 

 gradually to a fine point; size about 1"1 by '0127 millim.: forming part of longitudinal 

 skeleton-lines of surface -tufts." Styli (acuates) as long as those here mentioned appear, 

 however, to be very rare in the type, and considering the well-known irregularity of 

 the Axinellid spiculation in general we feel quite justified in not separating the two 

 forms specifically. 



Locality. — Off Bahia, shallow water. One specimen. 



Habitat.— Torres Strait ("Alert"); off Bahia (Challenger). 



Axinella Jibrosa, Ridley and Dendy (PI. XXXVII. fig. 3). 



1886. Axinella jihrosat Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 481. 

 Sponge (PI. XXXVII. 6g. 3) erect, massive, dividing into many lobes at the sum- 

 mit. Height of specimen 162 mm.; breadth 87 mm. Colour in spirit greyish-yellow. 



