A MONOGRAPH OF THE EXISTING CRINOIDS 241 



OLIGOMETnA SERRIPINNA tot. ELECTRAE A. H. Ctark 



Oligometra serripinna var. etectrae A. 11. Clark, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 51 (locality 



nomen nndum); Crinoids of the Indian Ocean, 1912, p. 174 (synonymy; locality); John Murray 



Exped. 1933-34, Sei. Reports, vol. 4, No. 4, 1936, p. 101 (range). 

 Oligometra eleclrae A. H. Clark, Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 38 Gocality 



characters) ; Unstalked crinoids of the Siboga-Exped., 1918, p. 129 (in key; range) ; John Murray 



E.xped. 1933-34, Sci. Reports, vol. 4, No. 4, 1936, p. 104. 



Characters.— This is an e.xceptionally ornate form with extravagantly developed 

 processes on the proximal pinnules. 



Locality. —Red Sea, southeast of Messawa, Eritrea (lat. 1.5°02'30" N., long. 

 41°13'30" E.); 36 meters; cable repair ship Electra [A. H. Clark, 1911. 1912 1913 

 1918] (1, B. M.). 



History. — This variety was first mentioned as Oligometra serripinna var. electrae 

 {nornen nudum) in a paper on the recent crinoids of the coasts of Africa published by 

 me in 1911, and also in my memoir on the crinoids of the Indian Ocean pubhshed in 

 1912. In both places the locality was given. Under the name Oligometra electrae 

 it was briefly characterized by me in a paper on the crinoids of the British Museum 

 published m 1913. In my report on the crinoids of the Siboga expedition published 

 in 1918 I inserted electrae in the key to the species of Oligometra, giving the Red Sea 

 as the habitat. 



OUGOMETRA SERRIPINNA CALEDONIAE A. H. Clark 



Anledon serripinna Hartlatjb, Nova Acta Acad. German., vol. 58, No. 1, 1891, p. 82 (Tonga Islands; 

 detailed description of the specimen.s), p. 113 (in Gottingen Mus.), pi. 5, fig. 48. 



Antedon cupulifcra (Liitken, MS.) Hartlaub, Nova Acta Acad. German., vol. 58, No. 1, 1891, p. 82 

 (name found with specimens from Tonga).— A. H. Clark, Vid. Medd. Naturh. Foren. K0ben- 

 havn, 1909, p. 179 (in synonymy of 0. serripinna); Crinoids of the Indian Ocean, 1912, p. 170 

 (in synonymy of 0. serripinna). 



Oligometra caledoniae A. H. Clark, Bull. Mus. Hist. Nat., Paris, 1911, No. 4, p. 254 (description; 

 New Caledonia); Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 28 (New Caledonia; dis- 

 cussion of this and similar varieties of 0. serripinna); Crinoids of the Indian Ocean, 1912, p. 175 

 (New Caledonia; description); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 39 (no locality; 

 Prof. J. B. Jukes) ; Unstalked crinoids of the Siboga-Exped., 1918, p. 130 (in key; New Caledonia 

 and the Tonga Islands). 



Oligometra serripinna (part) A. H. Clark, Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 27 

 (Tonga Islands; description of specimens and comparisons); Crinoids of the Indian Ocean, 

 1912, p. 172 (Tonga Islands.). 



Diagnostic features. — The segments of Pj have only a very slight spinous produc- 

 tion of the distal ends, which may be obsolescent; the distal ends of the pinnules 

 following P2 are not produced. 



Description. — The cirri are XI, 18-19, very short, rather stout, resembling those 

 of 0. sennpinna. The first segment is about twice as long as broad and those following 

 very gradually increase in length so that the eleventh to thirteenth and following are 

 about as long as broad. On the fifth the distal dorsal edge becomes slightly everted, 

 this oversion on the twelfth and following becoming a median transverse ridge that 

 appears as a minute spine in lateral view. The opposing spine is prominent, median, 

 and erect. 



The 10 arms are 83 mm. long and resemble those of 0. serripinna. 



Pi is slender, flagellate distally, with 21 segments which at first are short, becom- 

 ing about as broad as long on the fifth, the remainder being slightly longer than broad. 



