REPORT ON THE MONAXONIDA. 61 



Skeleton. — (a) Dermal; a reticulation of spiculo-fibre (PI. XVII. fig. 12) varying 

 from one to nine or ten spicules in breadth, and composed of stylote spicules. Over the 

 osculum-bearing pajjillae this reticulation is replaced by a single dense layer of closely 

 packed stylote spicules, mainly placed longitudinally and more or less parallel with 

 one another, {li) Main; composed of a coarse reticulation of thick, stout spiculo- 

 fibre, composed of stylote spicules like those of the dermal skeleton, but usually a little 

 shorter. 



Spicules. — (o) Megasclera; smooth styli (PL XVII. fig. 4) tapering to a not very 

 sharp point at the apex and also slightly towards the base, measuring about 0"7 by 

 0*0 19 mm. {h) Microsclera ; two kinds are present — (1) numerous large, contort 

 diancistra, measuring 0"1 77 mm. long by 0"019 mm. in breadth of shaft. The exact 

 shape of these spicules will be best understood from the figure (PI. XVII. fig. 2, a, h). 

 They occur both in the deeper tissues and in the dermal layer. (2) Very numerous, 

 small, contort spicules, many of which appear to be young forms of the large diancistra 

 (PI. XVII. fig. 2, d), while others (PI. XVII. fig. 2, <?), different inform, are certainly not 

 so; length of the latter 0"038 mm., and of the former about the same. The latter are 

 simply sigmata. Both forms occur abundantly in the dermal meml:)rane as well as in 

 the deeper tissues. In the dermal membrane they are so arranged as to leave frequent 

 spaces in which the pores are situated. 



In its very distinct and lace-like dermal membrane, strong, fibrous skeleton and 

 general external appearance, this sponge closely resembles many Esperellie, whence the 

 specific name. For a Vomerula it is very large. The large diancistra are like those of 

 Hamacantha (Hymedesmia) johnsoni, Bowerbank.^ Hamacantlia papillata, Vosmaer,^ 

 from the Arctic Seas, differs from Vomerula esperioides chiefly in the presence of 

 cylindrical spicules {tr. ^), but has the papillae. 



The sponge seems to grow in a very luxuriant manner on the Agulhas Bank, many 

 fine specimens having been obtained by the Challenger from that locality. 



Localities.— Stiition 142, December 18, 1873; lat. 35° 4' S., long. IS" 37' W.; 

 Agulhas Bank; depth, 150 fathoms; bottom, green sand; bottom temperature, 47°"0. 

 Two large bottles full. 



Station 320, February 14, 187G; lat. 37° 17' S., long. 53° 52' W.; off the mouth of 

 the Rio de la Plata ; depth, 600 fathoms ; bottom, green sand ; bottom temperature, 

 37°"2. A small fragment of a dark greenish colour, which, in accordance with its 

 spiculation, we identify with this species. 



1 Mon. Brit. Spong., vol. i. pi. v. fig. 112. 



2 Sponges of the " Willem Barents" Expedition, 1880-81, p. 28 {sep.). 



