142 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Aurivillius (1898) wrote that in March and April as well as at the end of October 

 the spermatozoa of this species were found in the water at Kristineberg, but at that 

 time the eggs were neither ripe, nor even partly ripe, so that he was unable to say 

 anything definite regarding the breeding season. This was, however, later determined 

 by Mortensen. 



Occurrence of the pentacrinoids. The first pentacrinoid of this species was found by 

 Grieg (1895) at Loksund in September 1892, attached to the brachiopod Waldheimia 

 (now Macandrevia) cranium. 



At Kristineberg, Fiskebackskil, Sweden, Dr. Th. Mortensen (1920) found that the 

 breeding season of this form is chiefly in August and September, though in 1919 ripe 

 specimens were found as early as July 23, and in January 1910 he collected a pentacri- 

 noid not yet quite ready for detachment from a Balanus growing on a shell of Pecten 

 maximus; this pentacrinoid he described in detail and figured in 1910. 



History. The commencement of the use of the naturalist's dredge on the Nor- 

 wegian coast was immediately rewarded by the discovery of this species, which was 

 first recorded by Prof. Michael Sars in 1835. He did not, however, distinguish it from 

 the Mediterranean form. Seven years later it was reported (also under the name 

 mediterranea) from the western coast of Sweden by Prof. Sven Loven, who mentioned it 

 only incidentally as a host for myzostomes. 



In 1846 it was described as a new species under the name of Alecto petasus by Profs. 

 Diiben and Koren, who had it from the Swedish coast near Fiskebackskil, and also from 

 Egersund and S0ndfjord in Norway. 



In 1861 Prof. Sars gave a detailed account of its occurrence on the Scandinavian 

 coast, noting that it is less common than the other characteristic comatulid of this 

 region, Hathrometra sarsi. 



In 1866 Dr. W. B. Carpenter wrote that this form is probably identical with the 

 species with which he was especially concerned, namely A. bifida. 



In 1873 Prof. Mobius reported it from Arendal, and in 1878 and 1879 Dr. V. Storm 

 recorded it from the outer part of the Trondhjemsfjord, beyond Galgenesset, in 40-100 

 meters. 



In 1881 Dr. P. H. Carpenter stated that this species is entirely distinct from A. 

 bifida, having more numerous cirri with slightly longer segments, relatively longer 

 brachials, more quadrate axillaries, and the two lowest pinnules (Pi and P 2 ) of more 

 nearly equal length. In 1884 he recorded a specimen from Triton station 3, and in the 

 same year Prof. Ludwig von Graff recorded another from Arendal, Norway, adding the 

 Kattegat to the list of localities from which this form is known in 1887. 



Dr. Fridtjof Nansen in 1885, in connection with his studies on the myzostomes, 

 recorded it from several new localities, and in the following year Drs. W. Kiikenthal and 

 Weissenborn recorded it from Bognestr0m. 



Further experience with the various forms of Antedon led P. H. Carpenter to doubt 

 the distinctness of bifida and petasus; in the Challenger report in 1888 he was inclined to 

 consider the two as identical, and bracketed their names together, though keeping them 

 separate in his list of known species of comatulids. 



In 1891 he decided that all the various forms of Antedon represent collectively but 

 a single species. 



Prof. D. C. Danielssen in 1892 noted that usually in A. petasus the rudimentary 

 ovum is partially surrounded by the nearest adjacent epithelial cells which, as the egg 



