PART 5 A MONOGRAPH OF THE EXISTING CRIXOIDS 591 



Sars expeditions of 1900 and 1902, and gave a very detailed discussion of its characters, 

 at the same tune correcting Koehler's records. 



Michailovskij in 1904 listed it from 4 Yermak stations, and Doderlein published 

 an excellent monographic account of the species in 1905, adding new localities resulting 

 from the work of the Helgoland. In 1907 Grieg recorded it from the Second Norwegian 

 Arctic Expedition in the Fram, 1898-1902, and from two stations of the Belgica cruise 

 of 1905, repeating these last records in 1909. 



In 1910 Mortensen recorded it from two stations of the Danmark expedition and 

 described some pentacrinoids in great detail. In 1912 the present author recorded it 

 from the dredgings of Dr. Wolfenden's yacht Silver Belle, in 1917 Mortensen summarized 

 its occurrence about Greenland, in 1914 Vaney noted it in the collections of the Pour- 

 quoi-Pasf, in 1917 Stephensen discussed its range, and in 1921 Grieg recorded it from 

 one of the stations of the 1910 expedition of the Michael Sars. 



In 1923 the author decided that this species was really nearer to the species 

 included in the Zenometrinae than to H. tenella, the type species of Hathrometra, to which 

 genus it had previously been referred; he therefore removed it to that subfamily 

 under the new generic name of Poliometra. At the same tune, he recorded it from 

 a number of new localities where it had been found by the Ingolf and gave a summary 

 of its range. 



Two weeks after the appearance of this memoir Dr. T. Gislen published a notable 

 contribution to the study of prolixa, recording it from no less than 19 new localities 

 and discussing its characters and affinities in great detail. He accepted the new 

 genus Poliometra and the reference of the species to the Zenometrinae, though with the 

 reservation, on the characters of the oral pinnules and cirri, that it is closely related to 

 the species of Hathrometra. He also suggested the recognition within the species of two 

 varieties on the basis of differences in the spicules in the pinnules. One of these varieties, 

 from Greenland and the Faroe Islands, with rather slender and smooth spicules, he called 

 var. groenlandica (that is, typical prolixa); the other, with coarse and extremely spiny 

 spicules, from Taimyr and the Kara Sea, he called var. sibirica. He noted that speci- 

 mens from Spitzbergen resembled those from Greenland in having slender spicules 

 which are, however, somewhat spiny. 



During the middle 1920's, Mortensen and Koehler gave accounts of the characters 

 and range of this species in their various works on European echinoderms. Some 

 additional records were provided by Grieg (1925) in his report on the collections of 

 the Blaajjeld and Tovik from the Spitzbergen Bank. 



In 1925 A. A. Schorygin recorded Hathrometra prolixa from two stations in the 

 Barents Sea, giving the depth and the character of the bottom. He noted that this 

 species is easily distinguished from Heliometra glacialis by the length of the proximal 

 pinnules as well as by the general form. 



In his memoir on the echinoderms of the Barents Sea published in 1928, Schorygin 

 said that Poliometra prolixa occurs only in the northern and central parts of that sea. 

 He gave the bathymetric range as from to 2000 meters, with the greatest repre- 

 sentation at 800 meters, the temperature range from 2.0 to +3.0 C., with the 

 largest representation at 1.0 C., and the bottom on which the species is found 

 ranging from mud through mud and stones to stones, with the largest number of records 

 on mud and stones. 



