284 DISCOVERY REPORTS 



Fig.C 



1. Perknaster aurorae, small specimen (R 40-50 mm.), St. 371. Abactinal spinelet, 0-63 mm., x 100. 

 I a. Actinal spinelet, 07 mm., x 100. ib, i c. Profiles of abactinal paxillae, 0-32 and 0-22 mm. high ; i c is a 

 secondary plate. 



2. Peryfewtw/erawrorae, large specimen, St. 366. Abactinal spinelet, 1-5 mm., x 50. 2a. Enlargement showing 

 spicules beginning to degenerate. 



3. 3a. Perknaster aurorae, "aberrant" specimen, St. MS 71. Two abactinal spinelets, 0-63, 0-55 mm., x 100 

 36. Actinal spinelet, forming part of a pedicellaria, 0-8 mm., x 50. 3 c. Tip of 3 6, x 100. 3(f. Profile of an 

 abactinal paxilla, pedicel 0-5 mm. (varying to 0-45 mm.); spinelet o-68 mm., x 50. 



4. Cycethra verrucosa, abactinal spinelets from various specimens, x 100. 4a. Specimen (R 25 mm.) from 

 St. M 71, South Georgia; spinelet 0-35 mm. 46. St. i6d. Shag Rocks; R 15 mm., 0-27 mm. long. 4c. St. 

 167. South Orkneys; R 44 mm., 0-45 mm. long. ^d. St. 123. South Georgia; R 75 mm., largest of the 

 Antarctic forms; 0-45 mm. long, ^e, 4/. St. 170. Marginal plates not superficially distinguishable from 

 abactinal or actinal plates; R 41 mm.; spinelets 0-45 and 0-38 mm. long. 4°. St. 55. Falkland Islands; 

 specimen with slender rays and small marginals similar abactinally to Koehler, 1923, pi. 7, figs. 5, 11, but 

 forma electilis actinally. 



5. Peribolaster folliculatus, x 10. Three adambulacral plates, near base of ray with ankylosed inferomarginals, 

 and 3 superomarginals {S) on right ; A 12-A 14, adambulacral plates 12-14, the fourteenth divided as happens 

 sporadically ; /, inferomarginal plates with the single long spine ; lowermost plate is cross-lined to show its 

 extent but there is no line of demarcation in the specimen. The broken line crossing the adambulacral marks 

 portion of inferomarginal fused to upper surface of adambulacral, which was identified in a smaller specimen 

 from St. WS 93. 



