TETRAXONIDA 3°? 



In these the spicules are smooth styli, with occasional spines near the base, o-2i-o-28 by 

 0-005-0-0II mm., tornota o-i8-o-2i by o-oo4-o-oo7 mm., and onychaeta varying in 

 length from 0-052 to 0-21 mm., not divided into groups of varying size. The specimens 

 here assigned to Tedania spinata (Ridley) vary in form from sub-spherical (rarely), 

 irregularly massive (rarely), branched, with stout cylindrical branches, to flabellate (the 

 typical form) or discoid and unattached. The surface is typically smooth, even, punctured 

 by commensal Amphipods and the dermis is typically tough and readily separable from 

 the underlying tissues. Oscules, usually of small size, may be found scattered generally 

 over the surface or, in flabellate and discoid forms, around the margins. 



The styli are, for the most part, smooth, but there is an occasional tendency to a slight 

 subtylostylote swelling to the base. In addition, spines may occur. The occurrence of 

 the spines is, however, not only rare but very sporadic. For example, in a single section 

 all the styli will be found to be smooth except for a small group situated at one point. 

 Or, again, the spicules may be smooth with perhaps two or three basally spined forms 

 found at rare intervals. Turning now to the holotype, the significance of this spining can 

 be readily appreciated. In sections taken at right angles to the substratum it is found 

 that the styli at the bases of the vertical columns are the most conspicuously spined and 

 those towards the surface are hardly spined at all. Moreover, small acanthostyli, re- 

 markably like those, to be described later, found in the embryos of the specimens here 

 assigned to T. spinata, are very occasionally to be found associated with the normal basally 

 spined styli set on the substratum. It seems probable therefore that the holotype of 

 this species represents nothing more than the immediate post-fixation form of the 

 species ; that there is retained in the adult a tendency to the formation of spines on the 

 styli, and that this tendency, although almost wholly suppressed in the adult, is yet found 

 in occasional spicules. 



Distribution. Chile. 



Tedania charcoti, Topsent. 



T. charcoti, Topsent, 1908, p. 30, pi. i, fig. 3, pi. iii, fig. 3, pi. v, fig. 6; 1913, p. 630, pi. v, 

 figs. 3-7; nee Topsent, 1917. 



Occurrence. St. 39: South Georgia, 179-235 m.; St. 140: South Georgia, 122-136 m.; St. 145: 

 South Georgia, 26-35 "i-; St. 146: South Georgia, 728 m.; St. 148: South Georgia, 132-148 m.; 

 St. 152: South Georgia, 245 m.; St. 158: South Georgia, 401-41 1 m.; St. 160: Shag Rocks, 177 m.; 

 St. WS 27: South Georgia, 106-109 m.; St. WS 42: South Georgia, 198 m. 



The nineteen specimens range from a few centimetres in longest diameter to nearly 

 20 cm. From the structure of the skeleton it is possible to divide this group into two 

 smaller groups; the first, of five specimens, is characterized by a dense skeleton and 

 thick spicules (styli 0-36-0-49 by o-02-o-03i mm.), with the dermal skeleton composed 

 of a very dense palisade of stout tornota (measuring o-32-o-39 by o-oi4-o-o2i mm.). 

 The second group, of eleven specimens, is characterized by a loose skeleton composed 

 of few spicules, mainly slender (styli o-35-o-52 by o-oii-o-o2i mm.), with a diffuse 

 dermal skeleton of slender tornota (measuring o-24-o-34 by o-oo7-o-oo9 mm.). There 



