454 SMITHSONIAN INSTITUTION 



CYDONOCR1NUS Bather 

 SYCOCRINUS Austin 



Dr. Bather in 1913 1 described a new genus, Cydonocrinus, and in 1914 2 redescribed 

 Austin's hitherto imperfectly known Sycocrinus, both from the upper Visean zone of the 

 British Lower Carboniferous. To the latter genus he refers the species Hypocrinus piri- 

 formis Rothpletz, from the island of Timor; and he ranges the two genera under the 

 Taxocrinidea for reasons given in his very full discussion of their characters. I have not 

 seen any of the specimens (the single one in the Austin collection not having been observed 

 by me when I examined that collection), but Dr. Bather's descriptions and figures leave 

 nothing to be desired. 



These forms are remarkable for the position of the anus, which opens laterally directly 

 through the dorsal cup and below the level of the radials, as in the Gasterocomidae. All 

 have three large infrabasals, of which the small plate is in the right posterior position. The 

 dorsal cup is globose or ovoid, strongly constructed, contracting at the arm bases to a narrow 

 tegmen, with no indication of any incorporation of brachials within it, either by lateral union 

 or by solid or perisomic interbrachial structures ; nor does there seem to be any place where 

 such structures might have rested. The shape of the radial facets indicates that the rounded 

 arms were free from their origin on the radials ; and one gets the same impression from 

 both Bather's and Austin's reconstruction of Sycocrinus {op. cit., 1914, PI. X, figs, id 

 and 2e). The tegmen is not known, but the space for it is greatly reduced, and the con- 

 struction at the margin indicates that it must have been rigid, probably like that of the 

 Cyathocrinidae. The only character which these specimens have in common with the 

 Flexibilia is the right posterior position of the small infrabasal. The position of this plate 

 is not constant, neither in the Flexibilia nor in the Inadunata. In the former it is usually 

 right posterior, but in some species of Forbesiocrinus, as elsewhere shown, it is anterior. 

 In Gissocrinus of the latter, as shown by Bather in The Crinoidea of Gotland, it is extremely 

 irregular. In Hypocrinus, from which he separates H. pyriformis chiefly on this character, 

 the small IB is anterior. But in Lecythiocrinus, from the American upper Carboniferous, 

 which specimens acquired since the original description show to have not only the same 

 type of anal opening, but also three infrabasals, the small plate is right posterior. In the 

 Inadunate family Gasterocomidae the infrabasals are unstable, often fused to 3 or 1 — most 

 frequently the latter according to my observation. 



The entire facies of these forms is opposed to that of the Flexibilia, and in every respect 

 where they differ from that group they agree with the Inadunata. The dorsal position of 

 the anus is unknown among the Flexibilia. While it is true, as Bather suggests, that this 

 does not preclude the discovery of such a form, yet when there is within the Inadunata such 

 a family as the Gasterocomidae, which will receive forms like this without violating funda- 

 mental conceptions, I must be pardoned for not being able to perceive sufficient reason for 

 referring them to the Flexibilia, with whose leading characters, according to my conception of 

 them, they are in nearly every respect in conflict. 



1 Ann. and Mag. Nat. Hist. 1913, p. 

 3 Ibid., 1914, p. 252. 



