A MONOGRAPH OF THE EXISTING CRINOIDS 241 



OLIGOMETRA SERRIPINNA vnr. ELECTRAE A. H. Clark 



Oiigometra serripinna var. electrae A. H. CLARK, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 51 (locality; 



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



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

 Oiigometra electrae A. H. CLARK, Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 38 (locality; 



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



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



Characters. This is an exceptionally ornate form with extravagantly developed 

 processes on the proximal pinnules. 



Locality. Red Sea, southeast of Messawa, Eritrea (lat. 1502'30" N., long. 

 4ri3'30" E.); 36 meters; cable repair ship Electro [A. H. Clark, 1911, 1912, 1913, 

 1918] (1, B. M.). 



History. This variety was first mentioned as Oiigometra serripinna var. electrae 

 (nomen 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 published in 

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

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

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

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

 as the habitat. 



OLIGOMETRA SERRIPINNA CALEDONIAE A. H. Clark 



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

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



Antedon cupulifera (Lutkeu, 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. K0hen- 

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

 (in synonymy of 0. serripinna). 



Oiigometra 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 O. 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). 



Oiigometra 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 P 2 have only a very slight spinous produc- 

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

 following P 2 are not produced. 



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

 of 0. serripinna. 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 eversion 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. 



P! 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. 



