270 TJie American Geologist. November. 1899 
Cystoidea are classed as nearest Crinoidea. Of the cystocri- 
tioidean genera Cariocrinus and Porocrinus come into consid- 
eration most appropriately here. The latter genus differs from 
true ciinoids only in the possession of pore-rhombs or water 
vascular organs on the abactinal wall of the calyx. Cariocrinus 
differs in that way, and also in the greater number of ambul- 
acral furrows and arms and radial plates. Compared to these 
Strophocrinus n. gen. shows no pores nor ihombs below the 
bases of the arms, although structures comparable to rhombs 
overlap upon the upper edges of the radials. In this respect, 
it is like Carabocrinus, if the drawings by W. Billings are right- 
ly understood (see lig. 18, pi. xii), but is none the less inter- 
mediate in type between Crinoidea and cystocrinoidean Cys- 
toidea. In Strophocrinus, three arms and radials are crinoidean 
and are acccrnpanied by complete crinoidean symmetry on 
the anterior side of the calyx. Two arms and radials are cysto- 
crinoidean, and they are associated with posterior azygous or 
supernumary plates among the radials, with a sixth basal and 
anchylosed sixth infrabasal. These characters are like Cysto- 
crinoidea possess, e. g. Cariocrinus, and yet differ from struc- 
tures in certain Crinoidea, not in kind but rather in degree. 
In Carabocrinus, fig. 18, pi. xii, a less complete but homolo- 
gous asymmetry is retained. In Dendrocrinus and Cyatho- 
crinus it is still evident, but reduced. 
Strophocrinus stands in the position of an intermediate or 
link between the composite of Cariocrinus, Porocrinus, et al., 
and the composite type of Cyathocrinoidea, including Cara- 
bocrinus. This places the azygos and anal plates of crinoids 
in a new light, and requires further explanation. 
Wachsmuth and Springer, in their "American Crinoidea 
Camarata," present the generally accepted view which is differ- 
ent from the one just mentioned regarding the azygous plates 
and space in the Crinoidea. 'Tn all dicyclic crinoids the basals, 
without exception, consist of five plates, the infrabasals either 
of five, three, or a single piece," they say (op. cit. p. 54), and 
in fact this account is skillfully enforced by the interpretation 
w^hich they outline. They recognize the homologue of five in- 
frabasals, or respectively basals, where a lesser number occurs, 
the lesser number being interpreted as fusion of adjacent in- 
frabasals or basals. However, "the case is not so sunple in 
