loo DISCOVERY REPORTS 



St. 474. One mile west of Shag Rocks, 199 m., i specimen. 



St. 1562. Marion Island, 46° 53' S, 37° 55' E, 97 m., 4 specimens. 



St. 1563. Marion Island, 46° 48-4' S, 47° 49-2' E, 101-106 m., 4 young specimens. 



St. 1564. Marion Island, 46° 36-5' S, 38° 02-3' E, 108-113 m., i specimen. 



This is one of the most handsome sea stars of the Antarctic. The paxillae are well 

 developed with numerous spinelets, of which those occupying the centre of tabulum are 

 characteristically clavate, heavier than the marginal spinelets, and in large specimens 

 quite crowded. The marginal plates can hardly be called paxillae. Rather they are con- 

 spicuous squarish blocks with a low broad tabulum crowned by many crowded spine- 

 lets, essentially like the abactinal but larger. The largest specimen (R 91 mm., St. 

 371) has paxillae and marginals with more numerous spinelets than Koehler's fig. 7, 

 pi. 7 (1912). The smallest specimen (St. 190) has R 5 mm. The characteristic thorny 

 tips of the spinelets are described and figured by Koehler. 



In the two large specimens (St. 371) each median "tooth" is accompanied on either 

 side by an accessory tooth, actually an enlarged suboral spine (sometimes upright, 

 sometimes bent slightly away from the mouth angle), the tip of which is hyaline. These 

 accessory teeth are developed in a specimen (St. 164) having R 48 mm., but the mem- 

 brane has not yet retracted from the tip. 



For a comparison of this species with Odontaster validiis, see the table of variations 

 under the latter. 



This is an Antarctic species. It is therefore not surprising that the young and 

 medium-sized specimens from Marion Island vary slightly from the Antarctic form. 

 For instance, there is an obvious lack of the slender spinelets which occur on the 

 margin of the paxillae of typical large specimens and which are indicated in Sladen's 

 fig. I, pi. 47. 



Koehler states that his specimens of elegans from the region between longitudes 92° 

 and 145° E (64^ 32' and 66° 55' S) are in no way different from the types which were 

 collected by the second Charcot Expedition in the Antarctic Archipelago. It is difficult 

 to understand why Koehler overlooked meridlotialis and compared his elegans only with 

 validiis. There can be no doubt that meridionalis and elegans are the same species. 



Epidontaster pentagonalis Koehler was dredged at St. 8, Australasian Antarctic Expe- 

 dition, 66° 8' S, 94° 17' E, 120 fathoms, at which Odontaster meridionalis v^&s taken. The 

 genus and species is based upon one young specimen having R 17 mm., r 10 mm., 

 characterized by having an accessory "tooth" on either side of the usual median tooth. 

 Otherwise it is a short-rayed O. meridionalis very similar to a young specimen (R 8-5 mm.) 

 from St. 170. This small specimen, which has the proportions of Koehler's, shows an 

 incipient accessory tooth on either side of the median. As noted above the two largest 

 specimens, from St. 371, each have the accessory teeth, the extreme hyaline tip of which 

 shows beyond the membranous envelope. In the larger of these two specimens R is 

 63 mm. ; in the other R is 58 mm. It follows therefore that the accessory teeth here, as 

 elsewhere in the Odontasteridae, are not of generic significance. 



Colour note. St. 164, orange yellow, Ridgway scale 170 y.c. 



