244 



"ENDEAVOUR" SCIENTIFIC RESULTS. 



they are actually oxea, it is not beyond possibility that, in the 

 present instance, he has inadvertently written "oxea" when 

 "styli" was intended. In either case, whether their spicules 

 be styli or oxea, the three sponges are, according to their des- 

 criptions, capable of being included in the genus W'ilsoncUa as 

 I ha\e defined it. 



The species of Wilsonella of which I ha\e a first-hand ac- 

 quaintance, appear to represent perhaps four or five generic 

 types, in accordance with the following division: — (i.) ]V. 

 australiensis : (ii. ?) IF. coitectens, sp. nov. ; (iii.) C. pyrumiila, 

 C. alata ; (iv. ) ]]'. ciirvicheJa, sp. nov., IT', oxyphila, sp. nov. ; 

 and (v. ?) C. dura. Of these the first-mentioned two species are 

 distinguished from the rest by the possession of isochelse 

 palmata? of typical form, and of toxa. 



In group (iii.) the chelae, whilst conforming rather to the 

 palmate shape, are peculiar in that they have an alate shaft 

 and undergo in the course of de\elopment a considerable 

 change of form.i To what extent their peculiarity in the 

 latter respect is. important one cannot say, since so little in- 

 formation concerning the growth-stages of chela? is available ; 

 but it seems to be the case that in Clathria proper, the youngest 

 visible forms of the chelae are not materially different (except 

 in the tenuity of their parts) from those which are fully 

 developed. It may be that the chelae of this group are 

 modified arcuate chelae ; for there is nothing objectionable in 

 the supposition that arcuate chehe may secondarily come to 

 resemble palmatce chehe, and in this connection it may be re- 

 marked that the immature forms of the chelte of C. pyramida 

 are much like those of the arcuate chela? of Lissodcndoryx 

 stipitata, Lundbeck.2 Chehe bearing a close resemblance in 

 both their immature and final stages to those of C. pyru]}iida, 

 but lacking in any perceptible modification of the shaft, occur 

 in Ampliilectus ceratosus, R. and D.'^; so marked, indeed, is 

 the resemblance between the chelae of these two species, that 

 the likelihood of its being merely an accidental one is remote. 



The species of groups (iv.) and [v.) agree among other 

 respects in possessing arcuate chelae which, moreover, develop 

 along similar lines. These chelae commence as a slightly 

 curved rod,'' upon which the rudiments of the alae appear 

 before there is any sign of the formation of the front palm. 



1 Vide Hentschel-ioc. cit-, pp. 376, 377, and figs. ISe, f. ^. 



2 Lundbeek— Porifera. Danish Ingolf Expedition, ii., 1905, pi. xvii.. fig. 2e. 



3 Ridley and Dendy- "Challenger" Monaxonida, 1887. p. 125. pi. xix., 



fig. 10a: Whitelegge, Austr. Mus. Mem., iv., 9, 1906, p. 473. 



4 The development of the chelse of Ectyodonjx mncvtatufi. Hentschel 



(1911), and of the ancorte of /of?-nr/io^(( variili'iis and /• n.rciitn, Lund- 

 beck (1905), commences in a similar manner. 



