TETRAXONIDA 305 



spicuous in several specimens that it is difficult to understand why Ridley and Dendy 

 should have failed to mention it. 



(An interesting case is shown in Fig. 19/ where the base of a specimen of T. tenui- 

 capitata is covered with an encrusting Haliclona sp. and the sponge has the superficial 

 appearance of certain specimens of T. massa.) 



Tedania vanhojfeni, Hentschel, has so much in common with certain specimens of 

 Paratedania tarantula that there can be little doubt as to their identity, but re-examination 

 of the type is necessary to establish this beyond doubt. Further, since the spiculations 

 of Tedania vanhoffeni and T. actiniiformis are so similar it is probable that the latter 

 may also be included eventually in the same species. 



Paratedania tarantula (Kirkpatrick), originally described from Victoria Land, has the 

 following well-marked characteristics: Form carrot-shaped, with most of the surface 

 covered by a thick, light brown cuticle and having a well-marked, equatorial pore area 

 immediately above the upper limits of the cuticle ; spicules all of large size. According to 

 the Hmits of the species established by me (1929, p. 441), which further research has not 

 caused me to modify, the dimensions of the spicules are: styli o-437-o-504 by o-oi8- 

 0-04 mm., tornota o-344-o-504 by o-ooy-o-oia mm., onychaeta of two sorts o-o64-o-i62 

 and 0-4-076 mm. These measurements are, on the whole, greater than those of any other 

 species hitherto described from the Antarctic or adjacent localities, except Tedania massa, 

 Ridley and Dendy. Further, in eight specimens from the present collection, typical in 

 all other respects, the sizes of the spicules are: styli o-63-o-78 by o-o28-o-04 mm., 

 tornota o-32-o-35 by o-ooy-o-oii mm., and onychaeta o-oy-o-zS and o-6-o-7 re- 

 spectively. The species seemed therefore to be characterized by the large size of its 

 spicules and by the peculiarities of external form. 



There are, however, several specimens which differ somewhat in external form but 

 which would necessarily be included in the species. Thus, in six specimens from South 

 Georgia, the form varies from carrot-shaped to massive and sub-spherical, with 

 the cuticle restricted to the base of the sponge (cf. also p. 304, Fig. 25). In these, 

 the dimensions, and other characters, of the spicules conform to the measurements given 

 above as typical of the species. On the other hand, there are from the Falkland Islands 

 eleven specimens, varying in form from carrot-shaped to massive and sub-spherical, with 

 the cuticle restricted to the base of the sponge, in which the spicules have the following 

 dimensions: styH o-46-o-59 by o-oi-o-oiy mm., tornota, 0-35 by 0-009 mm., and 

 onychaeta 0-07-0-19 and 0-4-0-6 mm. respectively. Thus, the styli here are noticeably 

 more slender than in those recorded above. 



(It may be noted here, that whereas most of the Falkland Islands specimens are 

 atypical in form, the onychaeta and tornota show the same characteristics, and the styli 

 the same tendency to modification to strongyla, though to a lesser degree, as the Ant- 

 arctic specimens.) 



Following on this are three specimens from the Falkland Islands having the skeleton 

 typical of Paratedania tarantula, but having a more atypical shape than the preceding 

 specimens. The smallest is spherical, 10 cm. in diameter, and the largest sub-pyramidal 



