Wachsmuth and Springer—Paleocrinoidea. 373 
We think the trigonal form in this case is fully explained by 
the absence of these two facets. The outline could not be 
otherwise, and for a similar reason it must be quadrangular in 
the four-armed Palowsk specimens. . 
The non-development ‘of a radial, which is found occasion 
Yy among specimens of the early types, is evidently, as Car- 
penter admits, due to their low organization, but for the same 
reason this feature cannot be of much value in considering the 
generic or even specific relations of these forms. 
Carpenter’s suggestion that Volborth’s organ was perhaps 
the anal opening seems to us to be sustained neither by embry- 
ology, nor by its own structure. When the Pentacrinoid larva 
of Antedon assumes the crinoidal type, almost contempora- 
Confess that we fail to-find any such analogy in. the so-called 
organ of Volborth. In the Erras specimen there is, in place of 
the one plate, a multitude of plates of the most doubtful origin, 
Grewingk. Schmidt’s figure, pl. 1, fig. 1, which is probably 
the most reliable, shows sions gaping crack through the middle 
* Researches in the Structure, Physiology and Development of Antedon (coma- 
ula Lamark) rosaceus, by W. B. Carpenter, M.D., F.R.S., Philosophical Transac- 
tions of the Royal Society, London, elvi, pp. 726 to 747. 
a 
