ASTEROIDEA 223 



grown examples of annulatus, in medium-sized examples of comparable size (e.g. 

 100 mm.) there is a decided difference in the dimensions of the largest crossed pedi- 

 cellariae. These are 0-55-0-65 mm. in radiosns and in ajinulatus, 0-9-1 -3 mm. In fully 

 grown examples of annulatus they are still larger (175 mm.). In addition to these large 

 pedicellariae there are also perfectly formed small ones on the order of 0-2 mm. long in 

 radiosus and o-27-o-4 in annulatus. Slight differences in details are observable in the 

 crossed pedicellariae of the two species (see figures). 



Fusion of the mouth-plates occurs in this species as in annidatiis and has been noted 

 and figured by Perrier (1891, p. 73, pi. 8, fig. 4). In a specimen with 34 rays and disk 

 diameter of 35 mm. (R 95 mm.) there are only 5 scattered furrows which are "open" 

 at the adoral end. There are rather fewer oral straight pedicellariae than in annulatus. 

 The adoral carina is composed of 5-7 pairs of adambulacral plates. 



Labidiaster crassus Koehler, without locality, seems to be a variety of radiosus with 

 stout, abnormally short rays. 



In the stomachs of several individuals from St. 51 were found the remains of Serolid 

 isopods. At this station were taken 3 species of Serolis — schythei, convexa, exigua (see 

 Sheppard, 1933, Discovery Report, vii, p. 259). There were 5 young Munida, looking 

 Wkt gregaria (identifications by Mr Dilwyn John). 



Distribution. The Falkland plateau and southern end of South America, north to 

 latitude 41° S on the Pacific coast and to 38° S on the Atlantic; 0-183 "i- 



Subfamily Coscinasteriinae Fisher 

 Coscinasteriinae Fisher, 1923, p. 249. — 1928, p. 93 (key to genera). 



Genus Lethasterias Fisher 

 Lethasterias Fisher, 1923, p. 258; 1928, p. 131. Type Asterias nantmensis Verrill. 



Lethasterias australis sp.nov. 

 (Fig. L, i-i^c', 2;PlateXVII, fig. 5) 



Diagnosis. R 32 mm., r 7 mm., br 7 mm. Resembling a small Sclerasterias abactin- 

 ally ; ray pentagonal in section, swollen beyond base. Differing from north Pacific forms 

 in lacking unguiculate straight pedicellariae, blackish tips to abactinal spines, and in the 

 different form of the straight pedicellariae which have a more extensive terminal Hp. 



Description. The type strongly resembles a small Sclerasterias but is debarred from 

 this genus by the presence of a cushion of crossed pedicellariae on both inferomarginal 

 spines and by the absence of even any sign of an enlarged lateral tooth on the terminal 

 lip of the crossed pedicellariae. In Distolasterias the crossed pedicellariae have an even 

 more conspicuously enlarged terminal tooth on each side of the terminal lip.^ The 

 abactinal surface slopes downward on either side of the carinal ridge to the supero- 

 marginal plates, each carinal and superomarginal plate carrying i stout capitate spine, 

 the swollen end being vertically grooved. Smaller, well-spaced dorsolateral spines are 



1 See Fisher, 1928, p. 95, pi. 60, figs. 1-3. 



