TETRAXONIDA 277 



Genus Calyx, Vosmaer 



Calyx arcuarius (Topsent). 



Gellius arcuarius, Topsent, 1913, p. 638, pi. vi, fig. 11; Calyx stipitattis, id., 1916, p. 171; 

 id., 1917, p. Si, pi. iv, fig. 13, pi. vi, fig. 24; Burton, 1929, p. 422, pi. v, figs. 5, 6. 



Occurrence. St. 39: South Georgia, 179-235 m.; St. 148: South Georgia, 132-148 m.; St. 149: 

 South Georgia, 200-234 m.; St. 159: South Georgia, 160 m.; St. 160: Shag Rocks, 177 m.; St. 163 : 

 South Orkneys, 18-27 "^-^ ^'^- '75 • South Shetlands, 200 m. 



Remarks. There are several specimens which correspond closely with the original 

 description of Calyx stipitattis and with the specimens recorded by me under that name 

 in 1929. They are all thinly flabellate, the largest 40 cm. high and about the same across, 

 with evenly rounded margins, often with rounded outgrowths springing from the main 

 body. The surface is even, glabrous or only minutely hispid. The skeleton is composed 

 of stout bundles of oxea, usually 20-40 deep, running from base to margin, branching 

 and anastomosing, with a confused triangular network of single spicules filling the 

 spaces between the bundles. The dermal skeleton is a tangential unispicular network, in 

 which the spicules are often irregularly set so that the ends frequently project slightly at 

 the surface. In this way, although there is a special dermal skeleton comparable with 

 that found in Adocia, the surface is minutely hispid. The oxea vary from o- 18 to 0-28 mm. 

 long by o-oii to o-oi8 mm. thick. 



The external form varies from branching, as in the specimen figured by me {loc. cit., 

 pi. V, fig. 6), to flabellate, and the disposition of the oscules may be on one of two plans, 

 a few conspicuous oscules (cf. Burton, loc. cit., pi. v, figs. 5, 6) or numerous small 

 oscules scattered over one surface only (cf. Topsent, 1917, pi. iv, fig. 13). I was wrong 

 therefore in regarding the "orifices circulaires" (1929, p. 422) as due to commensal 

 cirripedes. 



Calyx arcuarius, Topsent, is a species of varied form, with a dimorphic system of 

 exhalant apertures, and these different variations are well shown in the present series of 

 specimens. On the other hand, the main skeleton is constant in structure and forms a 

 character by which the species may be readily recognized. There can therefore be no 

 doubt that all the specimens before me at the moment are conspecific. In view of this, 

 the following observation is of particular interest ; namely, that some of these specimens 

 have abundant toxa, o-oy-o-i mm. long, some only a few, and some appear to be 

 entirely without them. It is obvious then that Gellius arcuarius, Topsent, and Calyx 

 stipitatus, Topsent, are synonymous, the holotype of the former being a fragment of a 

 large flabellate sponge having toxa in abundance, and the holotype of the latter being an 

 incomplete specimen having no toxa. We have to accept, as a consequence, the followmg 

 facts: that the members of the genus Calyx, a genus hitherto regarded as characterized 

 by the absence of microscleres, may possess toxa; that the absence of a particular 

 microsclere has, per se, no taxonomic value. 



Distribution. South Orkneys ; Victoria Land. 



