PLATYCRINTDAE 
55 
Section 2 . Subfamily MARSIPOCRININAE Bather 
Rays with only one primibrach. 
The next subdivision, with rays limited to a single primibrach, is abun- 
dantly represented by its earliest genus, remarkable for the manner in which 
its brachials to the axillary secundibrach are buried in the cup, so as to produce 
a thoroughly Camerate structure, and for the constancy with which its charac- 
ters are maintained throughout numerous species, now to be described. 
MARSIPOCRINUS Bather 
Plates 13-ip 
Marsupiocrinites Phillips (not de Blainville, 1830), in Murchison’s Sil. Syst., 1839, p. 672. — Austin, Ann. 
Mag. Nat. Hist., 10, 1842, p. 109. 
Marsupiocnntis McCoy, British Pal. Rocks and Foss, 1854, p. 54. — Wachsmuth and Springer, Rev. Pal., 2, 
1881, pp. 63, 230; N. A. Crin. Cam., 1897, p. 730. — Weller, Bull. Chicago, Acad. Sci., 4, pt. i, 1900, 
P- 137- 
Marsipocrinus Bather, Quart. Jour. Geol. Soc. London, 45, 1889, p. 173: Treatise on ZooL, 3, 1900, p. 156, 
fig. 70. — Bassler, Bibliogr. Index, Am. Ord. Sil. Foss., 1915, p. 786. 
Cupellaecrinites Troost, Am. Jour. Sci., 1849, p. 419; Proc. Am. Assn. Adv. Sci., 1850, p. 61 (not defined). — 
Cupellaecrinus Meek and Worthen (not Steininger), Proc. Acad. Nat. Sci. Phil., 1865, p. 161 ; Geol. 
Surv. Illinois, 2, 1866, p. 172. — Shumard, Trans. Acad. Sci. St. Louis, 2, 1866, p. 361 ; p. 387, footnote. — 
Meek, Am. Jour. Sci., 1866, p. 118. 
Platycrinidae with one IBr, small, axillary, and IIBr on either side of it 
resting on RR and wholly incorporated in dorsal cup, followed by another axil- 
lary in case of further division; one large iBr supported by shoulders of RR, 
flanked by smaller ones at upper corners which may be restricted to the tegmen ; 
arms stout, biserial, two or four to the ray, with large pinnules ; tegmen com- 
posed of numerous Anib. and iAmb. plates; anus subcentral, directly through 
the tegmen, without a tube; orals small, unsymmetric, pushed anteriorly, the 
posterior plate between the other four; stem circular in section, lumen large, 
usually pentagonal or peiitapetalous ; small basal at 1. ant. side. 
Genotype. Marsnpiocrinns coelatus Phillips. 
Distribution. Silurian to Lower Devonian ; England, Sweden, America. 
The name Marsnpiocrinns, proposed by Phillips for the English species, was preoccupied 
by de Blainville. Although Troost’s Ms. name, Cupellaecrinites, given for the form after- 
wards described by Roemer as Platycrinns tennesseensis, was adopted and published by AJeek 
and Worthen and by Shumard, it is held invalid by most authors for conflict with Cypellae- 
criniis of Steininger. Bather’s modification of Phillips’s name, proposed to remedy the exist- 
ing confusion, has been generally accepted. 
While the European Silurian has furnished some excellent examples for illustrating the 
structure of the genus, especially those figured by Angelin from Gotland, the little that has 
been published in regard to it in America has been far from commensurate with its impor- 
tance as now known. This has been due to the extreme rarity of specimens heretofore avail- 
able. Wachsmuth and Springer for the Camerata monograph had very meagre material, either 
of our own or in other collections. We had only two specimens with the tegmen preserved. 
