REPORT ON THE MONAXONIDA. 77 



This genus differs from Esj^erella only in having the chelate spicule equal-ended 

 instead of unequal-ended. The original type of the genus is EsjJeriopsis villosa, Carter, 

 a " Porcupine " sponge/ first described under the name Esperia villosa, and this has 

 been hitherto the sole species included therein. 



The Challenger adds six new species, and we must also include one old one, namely, 

 Esperiojms edwardii, Bowerbank, sp., represented in the collection by a new variety. 

 The synonymy of the latter sponge will be found under the species. 



Several of the species of this genus are remarkable for their well-defined external 

 forms, which serve as excellent guides l)y which to separate them from one another and 

 from others of the genus. 



The distribution of the genus is very wide, 1joth vertically and horizontally, but it 

 appears to prefer deep water in temperate or boreal seas. 



Esperiopsis symmetrica, Ridley and Dendy (PI. XIX. figs. 6, 6', 6o, 66, 6f; 

 PI. XXVI. figs. 4, 4a ; PI. XL VI. fig. 7). 



. 18S6. Esperiopsis STjmmetrica, Ridley and Dendy, Ann. and. Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 340. 



Sponge (PL XXVI. figs. 4, 4a) erect, straight, slender, cylindrical, unbranched (in 

 so far as evidenced by the Challenger specimens), covered with numerous, long, slender 

 sj)icular tufts, giving it the appearance of a bottle brush. The largest specimen is 

 44 mm. in length by 4 mm. in diameter (including the projecting processes, which are 

 themselves about 1 mm. in length). Colour in spirit dark chocolate-brown. Texture 

 fibrous and soft between the tufts of spicules. Surface closely beset with the projecting, 

 seta-like processes already mentioned. [Oscula and Pores unknown.) 



Skeleton. — Well seen in transverse or longitudinal section (PI. XLVI. fig. 7). Radiately 

 arranged. In transverse section the sponge is circular, and from its centre radiate 

 numerous loose bands of spiculo-fibre, after the manner of the spokes of a wheel ; these 

 fibres (PI. XLVI. fig. 7, d) project far beyond the surface of the sponge, thus causing the 

 hairy appearance. At a short distance within the circumference of the sjionge itself is a 

 regular circle, formed by the cut ends of longitudinal bands of spicules; each group of 

 cut ends occupying one of the segments between two- radiating fibres. At a short distance 

 outside this circle, just beneath the surface of the sponge, is another similar but much 

 less regular circle of cut spicules. The longitudinal fibres of the skeleton are confined 

 almost exclusively to these two sheaths, placed one within the other; the inner (PI. XLVI. 

 fig. 7, h) Ijeing fairly compact and well defined, but the outer (PL XLVI. fig. 7, c) irregular 

 and diffuse, while sometimes the two run into one another. There are no definite 

 longitudinal fibres in the centre of the sponge, but a few loose, more or less longitudinally 

 placed spicules. 



1 Ann. and Mag. Nat. Hist, ser. 4, vol. xiv. p. 213, pi. xui. figs. 13-15 ; pi. xv. fig. 36. 



