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



rather abruptly (hastately) pointed, measuring about 0"22 by 0'0063 mm., occurring in 

 the surface brushes. 



This is a very pretty and well-characterised species, which may be readily recognised 

 by its external form and more especially by the arrangement of the oscula. From the 

 number obtained by the Challenger it would seem to be abundant near Port Jackson. 



Judging from the description and from a preparation of that species, it would appear 

 to resemble Spongia caliciformis, Lamarck, most nearly of described forms, Ijut that 

 species, as yet only known from the North Sea, is cup-shaped. 



Locality. — Port Jackson ; depth, 30 to 35 fathoms. Eleven specimens. 



Phakellia papyracea, Ridley and Dendy (PI. XXXVI. fig. 4). 



1886. Phaliellia papyracea, Eidley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 478. 



Sponge (PL XXXVI. fig. 4) very thin, lamelliform. Eepresented in the collection by 

 fragments only, ^jossibly cup-shaped when alive ; perforated all over by very numerous, 

 minute, round (1 oscular) openings. Alike on both surfaces. Thickness of lamellae 

 about 2 mm. Colour in spirit yellow or brown. Texture fragile. Surface fairly 

 even, very minutely hispid. Oscula (?) very abundant on both surfaces, minute. 



Skeleton. — Reticulate, rather vague and indefinite ; distinct fibres present but very 

 loose, composed of large stylote spicules, with spicules of a smaller size scattered between, 

 or also in loose fibres. There is no special dermal skeleton, l)ut the small stylote 

 spicules are very much more abundant at the surface than elsewhere, especially 

 around the oscidar (?) openings. 



Spicules. — Mcgasclera; of two kinds; (1) large, stout, smooth styli, rarely subtylo- 

 stylote, usually more or less curved and faii-ly gradually sharp-pointed, size about 07 by 

 0"02 mm. (2) Much smaller and slenderer styli or subtylostyli, commonly rather 

 crooked; sharply and fairly gradually pointed; size variable, say about 0'35 by 

 0'0063 mm. but often much smaller. 



This is a very delicate species, which perhaps comes near to Bowerbank's Isodictya 

 itifmidibidifonnis,^ more especially if it should ultimately prove to be cup-shaped when 

 perfect, but it is distinguished at once and absolutely from that species by the alisence of 

 the oxeote spicules, so that further comparisons are needless. In the absence of the 

 oxeote spicules, however, it agrees with von Marenzeller's Cribrochalina ambigna,^ but 

 diff"ers widely in the size of the spicules, which, in Cribrochalina ambigua " sind Stifte 

 von 0"23 bis 0"34 mm. Liinge," while there do not seem to be two distinct sizes as in our 

 sponge. 



Localities.— Station 145a, December 27, 1873; lat. 46° 41' S., long. 38° 10' E.; oflp 



' Jlon. Brit. Spong., vol. ii. p. 317 ; vol. iii. pi. liv., &c. 



- Poriferen, Anthozoen, Ctenophoren iind Wiirmer, von Jan Mayen ; Vienna, 1886, p. 1, pi. i. fig. 1. 



