1:^2 "ENiJEAVOUR" .SCIENTIFIC RESULTS. 



ture of the skeleton to distinguish it generically from certain 

 species at present included in the genus AxificlUi. 



The three sponges described b}' Lendenfeld^ under the name 

 ot Echinonema iDichomtiini, Carter, have, according to their 

 description, the spiculation of Clatlirissu, but the skeleton is 

 reticulate. The best plan to adopt in regard to these sponges 

 is to regard them as species dnbicc of WilsonclUi (i^.v.). 



(iEXUS Ckei.la, Gray. 

 Thiele2 has expressed the opinion that Pliiniolialichoiuhiti 

 incriistans, Carter, should be placed in the genus Pytheas 

 which, as Lundbeck has recently shown, must now be called 

 Crella. Accordingly I employ the latter name for the sponges 

 about to be described. These agree so closely in the charac- 

 ters and dimensions of their spicules that, despite considerable 

 differences in some other respects, they might very well be 

 treated — in contrast with other species of the genus — as 

 \arieties of a single species, Crella incriisians. In this species, 

 as in Clathrissa arhiiscuhi the smooth oxeote spicules are 

 secondarily diactinal. 



Crella ixckustaxs, Cartvi\ et \ akk. 

 (Plate xxiii., ligs. J, 3; Plate xxiv. ; and hgs. _'S-34.) 



General cliuiiiiusis : Kxler)ial form various: e}icrusti)igy 

 massive or ramose. Oscula present in probably all the 

 varieties. Typically {unless in encrusting varieties) the 

 branching ascendent fibres of the main skeleton are 

 sinuous and interosculate so as to form a kind of loose 

 reticulation {pseudo-reticulation) ; connecting fibres, in 

 small number, rnay occur. The fibres are fairly closely, 

 sometimes extremely densely, echinated ivith straight 

 conical acantho style s ; the coring spicules may be exclu- 

 sively smooth oxea, or exclusively acatithostyles, or a 

 mixture of botJi. Foreign particles are in some cases 

 included in the fibres. The dermal skeleton is a layer of 

 shorter {usually slightly curved) acantJiostyles, ivith a 

 reticulate or more or less confused arrangement, rarely 

 accompanied by relatively fezv smooth oxeote s. All three 

 kinds of megascleres occur inter stitially, the dermal acan- 

 thostyles typically in greatest abundance. The micro- 

 scleres are of a single kind, isochelce arcuatce, scattered 

 inter stitially and in the dermal layer in moderate abund- 



1 Lendenfeld-Oat. Spnnefs Austr. Mus.. 1888. p. 219. The three sponges 

 referred to bear the varietal names, rnmosa, dio-a and lameUnsa. Their 

 type-si^eeimens appear to have been lost, since the specimens which 

 Whitelegge regarded as such cannot at all l)e reconciled with 

 Lendenf eld's descriptions (vidf .\ppendix). 



2 Thiele— Archiv. Naturg.. 1903. p. 388. 



