RETEOCRINIDZ&. 175 
extent by hard matrix; and we are unable to say at present to what genus 
they belong. 
8. A. Miller, in his arrangement of the Lower Silurian Camerata in 
1883,* united Reteocrinus and Xenocrinus with Areheocrinus, Cupulocrinus, 
Glyptaster, Glyptocrinus, and Lampterocrinus in one family, under the “ Glypto- 
crinide.”’ It is not clear to us upon what this classification was based, since 
the author did not discriminate between the presence or absence of infra- 
basals as a family distinction, nor between a regular or irregular arrange- 
ment of the interradials; nor did he give attention to the structure of the 
anal side, upon which most writers, and Miller himself, have relied for 
excellent family characters. In a later paper on Giyptocrinus and allied 
forms,t he states that the presence or absence of “subradial” plates, the 
presence or absence of “secondary radials,’ the structure and form of the 
column, and the presence or absence of a “ proboscis,” are the principal 
characters upon which “ the genera of this special group” have to be separ- 
ated. All of these rules are in a greater or less degree infringed by Miller 
himself. His ‘“ Glyptocrinus” parvus has infrabasals ; his ‘“Glyptocrinus Forn- 
shell, a pentangular stem instead of round as in the typical species. A “ pro- 
boscis,” such as occurs among the Actinocrinide, does not exist at all in this 
group, or at least has not been observed. Neither do we find that the 
proximal distichals are ever free arm plates, as Miller claims to be the case 
in “ Pycnocrinus.’ ‘The specimens which he refers to this genus, and which 
he kindly sent us for comparison, have from one to two interdistichals, and 
necessarily had “secondary radials.” 
In Miller’s classification of 1889,+ the “Glyptocrinide” embrace the 
genera Archeocrinus, Glyptocrinus, Compsocrinus, Pycnocrinus, and Schizocrinus, 
which, as we think, are representatives of almost as many families. He 
there makes Xenocrinus the type of a distinct family, refers G/yptaster and 
Lampterocrinus to the Glyptasteride, and places Gaurocrinus, Reteocrinus, 
Raphanocrinus, and Thysanocrinus under Gaurocrinide. 
The Reteocrinide are restricted to America, where only seven species 
have been discovered. 
* Amer. Palsoz. Foss. (ed. 2), p. 276. 
+ Dec., 1883; Journ. Cincin. Soc. Nat. Hist., pp. 218-219. 
¢ North Amer. Geol. and Paleont., pp. 214 to 215. 
