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



restore the latter designation.^ Tlic Crustacea that constantly occur in the large lumen 

 of the tube, Semper identified as a Palseraonid, along with which there frequently occurs 

 an isolated Aega, named by him Aega spongioi^hila. 



In the same year (1867), in his attempt to form a general system of the sponges,^ 

 Gray erected an order of "Acanthospongise" in which "spicules of more than one form or 

 kind" appear " in the same sponge," and to this he referred, among others, a special family 

 of the Euplectellidas with the following characteristics : — " Sponge tubular, skeleton 

 composed of longitudinal, transverse, and oblique bundles of spicules, intersecting each 

 other and forming a network. Sarcode mucilaginous, studded with many rayed stellate 

 spicules." To this family Gray also referred, in addition to the genus Eiqylectella, two 

 other new genera, CorhiteUa and Heterotella, which differ from Euplectella chiefl}^ in the 

 absence of the regular longitudinal and circular disposition of the fibrous skeletal 

 strands. The diagnosis of the genus Euplectella is given by Gray ^ as follows : — • 

 "The tubes regular, gradually wider above, formed of regular longitudinal and transverse 

 bundles of filiform spicules, which are crossed in an oblique direction with more slender 

 fascicles or separate filiform spicules, and strengthened externally with transverse or 

 obliquely raised ridges ; the upper ridge forming a fringe at the top of the tubes, between 

 the edge of the tubes and the irregularly netted lid. Sarcode thin, studded with many 

 rayed stellate spicules, with long simple or trifid rays, or with short rays divided at the 

 end into several converging rays, forming a bell-shaped series." 



As specific examples Euplectella aspergillum, Owen, and Euplectella cucumer, Owen, 

 are cited. 



In 1868, Glaus published a detailed research on the architecture, formation and 

 structure of the skeleton of Euplectella aspergillum, Owen.* The different forms 

 of spicules are intimately described, and the fusion of certain groups by the deposition of 

 siliceous lamellfe is demonstrated. 



In Bowerbank's critique on Gray's ari-angement of the Sponges,* the separation of the 

 family of the Euplectellidse from the " siliceo-fibrous sponges " is censured, since their 

 skeleton is " truly siliceo-fibrous." 



A new Japanese species belonging to the genus Eiq^lectella has been described by 

 Herklots and Marshall,* under the name of Euplectella oweni. It is characterised both 

 by its saccular form, which gradually diminishes upwards, and by a peculiar arrangement 

 of the round parietal pores, with which variations in the skeletal structure are associated. 

 In this species there is no cementing of the long siliceous spicules into longitudinal 

 fibrous strands, and in place of the outwardly directed oblique ridges there are downy 

 siliceous hairs covering the surface. 



1 Archivf. Naturgesch., vol. i. pp. 84-89, 1867. ^ Proc. Zool. Soc. Land., pp. 492-558. 



2 Loc. cit., p. 528. ^ Ueber Euplectella aspergillum, p. 4, 1868. 



^ Proc. Zool. Soc. Lond., p. 118, 1868. ^ Archives nderland Sc. exact, etnatur., vol. iii. p. 458. 



