SYSTEMATIC PART. 159 
one; the remaining ten genera have simple radials throughout. Neither do 
we find any remarkable development of certain radials, except when these 
are compound. All this is seriously in the way of making the presence or 
absence of infrabasals a subordinal character. 
Bather claims that among the Dicyclica departures from the pentamerous 
symmetry of the cup plates occur only in the right posterior radial. Excep- 
tions to this, however, are found in Atelestocrinus and Nanocrinus, in which 
the symmetry is disturbed by the anterior radial, and in the latter genus by 
the right antero-lateral together with the anterior. 
Bather’s researches were largely devoted to the Dicyclica of the Niagara 
and Wenlock age, which he divided into three principal families: the ‘ Den- 
drocrinide,” the “ Cyathoerinide,” and the “ Decadocrinide ;” and in addi- 
tion to them he recognized two smaller families, the “ Euspirocrinide ”’ and 
“ Carabocrinide,” the latter unrepresented in Europe. 
The Dendrocrinidx are defined by him as follows: “ Dicyclica, with R’ 
alone, or with anal z alone, or with RA’ and anal a, or with a radianal, anal 
x and one plate of the tube, in the anal area of the dorsal cup; with broad 
radial facet ; with dichotomous arms, that may or may not develop pimnules; 
with a tegmen composed of small plates, and with a ventral tube that is 
unusually long and transversely flattened.” He states that the family is 
distinguished from the Decadocrinide by the continuous dichotomy instead 
of the single bifurcation of the arms; that their anal x, unlike that of the 
Cyathocrinide, is always associated with other anal plates; that the radials 
have a wide, slightly specialized facet; and that their tezgmen is more 
delicate. The Dendrocrinid are said to be represented in America in 
the Hudson River group by Dendrocrinus, in the Devonian — both in this 
country and in Europe — by Homocrinus, and in the Carboniferous by Pari- 
socrinus, Poteriocrinus, and Scaphiocrinus, which agree in the structure of the 
anal area; the three latter with pinnules, the former without them. The 
presence or absence of pinnules, and the structure of the arms, he makes the 
leading characters for distinguishing the genera. 
He defines his second family, the Cyathocrinidx, as having “no radianal 
or tube plate in the anal area of the dorsal cup; with anal z either pres- 
ent in the cup or raised above it; with five arms, simple and dichoto- 
mous; with tegmen rather solid.” He refers to it Cyathocrinus, Gissocrinus, 
and their descendants, with the subdivisions Cyathocrinites, Achradocrinites 
and Codiacrinites, of which the latter have no anal at all, and some of their 
genera have an inferradial, or a radianal; while others have not. 
