252 DISCOVERY REPORTS 



Koehler has materially added to the knowledge of this species, and a rather full 

 account is given in his Kerguelen paper. In his report on the results of the Swedish 

 Antarctic Expedition he includes a 6-rayed form from Antarctic Bay, South Georgia 

 (1923, p. 33, pi. 13, fig. i) which, apart from the number of rays, more closely resembles 

 D. brucei than meridionalis. Similar specimens have been listed in this report under 

 brucei. In typical meridionalis there are numerous stubby irregularly scattered dorso- 

 lateral spines subequal to the carinals which are not aligned in a sharply differentiated 

 fairly regular longiseries. In the problematical specimens the carinal spines are heavily 

 stoled, are in as regular a series as in brucei and are occasionally even more sharply 

 differentiated from the smaller dorsolateral spines. In my specimens the differentiation 

 is more marked than in Koehler's figure ; and the cushion of tissue around the spines is 

 in one case (St. MS 71) distinctly larger than in brucei, where it is variable in size — not 

 rather constant as Koehler thought. In brucei there is a series of actinal spines. In meri- 

 dionalis there are no actinal spines, and the plates are small, wedged between the well- 

 developed inferomarginals and adambulacrals, and invisible in alcoholic specimens. 

 But young specimens of brucei do not have any actinal spines, and if small enough, no 

 actinal plates either. As the pedicellariae are very similar in the two species there will 

 always be great uncertainty in determining young 6-rayed specimens. Since meri- 

 dionalis also has a few 5-rayed young it is obvious that these will be confused with young 

 brucei until adult characters are developed. 



A typical specimen from St. MS 10 (14 February 1925) with R no mm. has 50 young 

 in the nidamental cavity; 46 have 6 rays and 4 have 5 rays. From St. 140 are 2 small 

 7-rayed specimens, placed in this species rather than octoradiata on account of pre- 

 ponderance of diplacanthid adambulacrals. 



A specimen from St. MS 6, having R 105 mm., is occupied by 3 large parasitic 

 ascothoracid cirripedes, Dendrogaster , lying in the coelom. The central portion of each of 

 the 4-branched bodies lies between the dorsal and ventral stomachs, while the space 

 between the hepatic diverticula and the ventral wall is completely filled (for half or 

 three-quarters length of ray) by the many lobed branches. Branches of the upper parasite 

 extend into rays i, 2, 4, 5 ; while the middle occupies rays i, 4, 5, 6 ; and the lowermost, 

 rays 3 (2 branches) 5, 6. Ray 6 therefore is crowded with a branch of each parasite. In 

 spite of all this competition for space the hepatic diverticula appear to be normal and all 

 ID gonads functional. It is difficult to understand how the stomach could have func- 

 tioned adequately. The body wall is flaccid and the elements of the skeleton are weak — 

 precisely the condition which I found in an almost equal-sized Leplasterias polaris 

 acervata, from Bering Sea, parasitized by several large Dendrogasters ; and in a specimen 

 of Hippasteria calif ornica (Fisher, 191 1, p. 237, pi. in, fig. i) containing one large 

 D. arbuscula. 



Distribution. South Georgia ; Marion Island ; Kerguelen (type locality) ; low tide to 



234 m. 



