4 
MUSEUM BULLETIN No. 31. 
of the two kinds. The column is 2-55 mm. in diameter, at a point 
2-5 mm. from a crown 26 mm. long. 
Class, Edriosasteroidea Billings (emend. Bather). 
Olarke has shown that the Devonian species of Agelacrinites 
differ from the Ordovician forms which have been referred to that 
genus in having mosaic, instead of imbricating, plates. Since the 
type of Agelacrinites is a Devonian species, it has become necessary, 
as Olarke 1 2 - and after him Foerste^ pointed out to make provision for 
the Ordovician forms. This need was in part met by the genns 
Lebetodiscns proposed by Bather 3 after studying the incomplete 
specimen of Agelacrinites dichsoni collected by Bigsby and figured 
by Billings. 4 
In a paper on the species of “Agelacrinites” found in the Trenton 
of Ontario 5 this generic name was used for all the forms there des- 
cribed but it was suggested that the name Lebetodiscns be restricted 
to the type-species and L. lorifarmis , and that two new genera be 
created for the other species. Dr. Foerste had been working for some 
time on the Ordovician Agelacrinitids and the writer, therefore, 
refrained from naming the genera thus forecasted. In a paper which 
has just appeared® (April 5, 1917) Dr. Foerste has supplied the two 
generic names wanted. 
Genus, Lebetodiscus Bather. 
Type, Agelacrmites dichsoni Billings. 
'Specimens of this species are rare and the best one known is 
that figured by the late Sir James Grant in the Ottawa Field 
Naturalist. This specimen, which was donated to the Yictoria 
Memorial Museum, appears after comparison with Billings’ and 
Bather’s figures, to be a real Agelacrinites dichsoni. Bather states 
that Lebetodiscns differs from Agelacrinites in three essentials: 
(1) the absence of a differentiated marginal zone; (2) having a less 
flattened and less sessile habit, and (3) “ the side plates, here called 
flooring plates, are homologous with the flooring plates of Edrioaster. 
Whether those plates have homologuesi in the Agelacrinidse is a 
matter for debate; at any rate, no genns of that family has similar 
plates with intervening depressions so like pores.” The first two 
1 Bull. N.T. State Mus., 49, 1901, p. 182, 
2 Bull. Sc. Lab., Denison Unlv., vol. 17, 1914, p. 399. 
s Geol. Mag. dec. 5, vol. 5, lSW, p. i&'&O-. 
4 Canadian organic remains, dec. 3, l'&&8, PI. S, figs. 4, 4a. 
c Ottawa Naturalist, vol. 24, 1915. 
g Bull. Sc. Lab., Denison Univ., vol. IS, 1917, p. 340 (dated Dec., 1916). 
