PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 341 



MoRTENSEN, Vid. Medd. Nat. Foren. K0benhavn, vol. 72, 1920, p. 78 (discussion of elongate 

 marginal cirri). — F. W. Clarke and Wheeler, U.S. Geol. Surv. Prof. Paper 124, 1922, p. 20 

 (inorganic constituents of the skeleton).- — A. II. Clark, The Danish Ingotf-Kxped., vol. 4, No. 5, 

 Crinoidea, 1923, pp. 6, 42 (range), p. 52 (in key). — Gisl£n, Ark. Zool., vol. 15, No. 23, 1923, 

 pp. 8, 9; Zool. Bidrag Uppsala, vol 9, 1924, pp. 36, 39, 85, 92, 288. — Mortensen, Danmarks 

 Fauna, No. 27, 1924, p. 20, p. 21 (in key). — Djakonov, Trav. Soc. Nat. Leningrad, vol. 56, pt. 2, 

 1926, p. 107 (in key). — Derjugin, Proc. Congr. Zool. Anat. Histol., U.S.S.R., vol. 2, 1927, p. 

 268. — Mortensen, Handbook of the echinoderms of the British Isles, 1927, p. 26 (in key), p. 35 

 (diagnosis). — Koehler, Les dchinodermes des mers d'Europe, vol. 2, 1927, p. 116 (in key), p. 

 129 (diagnosis). — Gisl^n, Vid. Medd. Nat. Foren. K0benhavn, vol. 83, 1927, pp. 5, 50; Ark. 

 Zool., vol. 19, No. 32, 1928, p. 11. — A. H. Clark, Journ. Linn. Soc. (Zool.), vol. 3G, 1929, p. 

 660. — Djakonov, Les 6chinodermes des mers arctiques (in Russian), Leningrad, 1933, p. 22 

 (in key). — Gorbunow, Trans. Arctic Inst., Leningrad (in Russian), vol. 8, 1933, p. 41. — Tob- 

 TONESE, Natura, Milano, vol. 24, 1933, p. 163. — A. H. Clark, Explorations des mers de I'U.R.S.S., 

 vol. 23, 1937, p. 218 (in key), p. 222 (in Russian), pp. 222, 224, 230 (English translation).— 

 Gisl^n, Kungl. Svenska Vet.-Akad. Handl., ser. 3, vol. 17, No. 2, 1938, p. 21. — Tortonese, 

 BoU. Mus. Zool. Univ. Torino, vol. 46, ser. 3, No. 82, 1938, p. 45 (brief diagnosis). — Schorygin 

 in Gaevskoy, Check list of the fauna and flora of the northern seas of the U.S.S.R. (in Russian), 

 1948, p. 470. — Djakonov, Bull. Pacific Inst. Fish. Oceanogr., Vladivostok, vol. 30, 1949, p. 13 

 (in key). — Gisl£n, Rep. Swedish Deep Sea Exped., vol. 2, Zool., No. 4, 1951, p. 55. — Hyman, 

 The invertebrates, vol. 4, Echinodermata, 1955, p. 97 (characteristic of arctic and northern 

 waters). 

 Helometra A. H. Clark, Explorations des mers de I'U.R.S.S., voL 23, 1937, p. 229. 



Diagnosis. — A genus of Heliometrinae in which the brachials are about as long as 

 broad or longer and, like the elements of the division series, are without carinate proc- 

 esses or spinous borders; Pi is composed of 50 to 100 segments of which only the terminal, 

 if any, are longer than broad; P2 is similar in size to Pj (except in some very small speci- 

 mens) ; the middle and distal pinnule segments are not much longer than broad; and 

 there are five radials and ten arms. 



Tyj)e species. — Alecto eschrichtii J. Mtiller, 1841 (a synonym of A. glaeialis Owen, 

 1833). [Note by A.M.C] In checking on the proper nomenclature of the type 

 species of this genus, I found that Mr. Clark was mistaken in thinking that Leach's 

 catalogue of the museum of the Royal College of Siu-geons, published in 1830, included 

 a description of the digestive system on page 14 with the locahties of the Dorothea and 

 Trent specimens. It was Owen in the catalogue of the physiological series in the same 

 museum, published in 1833, who included such a description under the heading of 

 Alecto glaeialis. Although this description was said to be of the digestive system of 

 "the genus Alecto" it was clearly derived from Leach's specimens which were those in 

 the museum of the Royal College of Surgeons. Strictly speaking, the anatomical 

 description would fit most comatulids, but under the rules of nomenclature similar 

 unprecise indications have been accepted as sufficient foundations for maintaining other 

 specific names. Alecto glaeialis can therefore be said to be valid, but with Owen as 

 author, not Leach, who simply noted that one "was a very fine and perfect specimen" 

 (a statement that cannot be construed La any way as a description) and gave two 

 localities for his material. Since 1908, when Mr. Clark unfortunately revived the name 

 glaeialis Leach in place of the well-founded eschrichtii Miiller, 1841, the majority of 

 people, headed by Mortensen and Grieg, have adopted the name TIeliometra glaeialis, 

 although in 1915 von Hofsten declared that glaeialis is a nomen nudum and reverted to 

 eschrichtii Miiller, followed by Gisl6n (1923 and 1924) and Koehler (1924 and 1927). 

 Accordingly in this monograph I am leaving Mr. Clark's terminology but am changing 

 the name of the author of glaeialis from Leach to Owen. Two specimens from the 



