I 12 
SMITHSONIAN INSTITUTION 
Eucheirocrinus chrysalis (Hall) 
Plate 2p, figs, i, la-c, 2, g 
Chcirocrinus chrysalis Hall, i3tli Rep. New York St. Cab. Nat. Hist., i860, p. 122, diagrams 1-5; 28th 
Rep., 1879, P- 147. fig- 2. — Eucheirocrinus chrysalis, Meek and Worthen, Proc. Acad. Nat. Sic. Phil., 
1869, p. 73; Geol. Siirv. Illinois, 5, 1873, p. 443, 502. — Proclivocrinus chrysalis Ringueberg, Ann. 
New York Acad. Sci., 4, 1889, p. 399 (12), pi. 10, figs. 2, 13. — Proclivocrinus radictilus Ringueberg, 
ibid., p. 397 (10), pi. ?, fig. 6. 
The genotype. To facilitate comparison of the generic characters I am 
figuring the type specimen from the Rochester shale of the Silurian at Lock- 
port, New York, together with some others from the same locality. In the type 
the suture dividing the left BB is indistinct, but can be seen in strong sunlight. 
In these specimens the outer articulating face of the axillary primibrach ex- 
ceeds the inner in width about as 4 to 3. I also give herewith some diagTams to 
illustrate the variations in arm structure of this and the two species showing 
the greatest departure from type, E. Ontario and E. anglicus. 
a. p c. 
Fig. 3. Varieties of Arm-Branching in Eucheirocrinus. a, E. chrysalis; h, E. Ontario; c, E. anglicus 
Eucheirocrinus minor new species 
Plate 2g, figs, g, ga, b 
A small species. Crown 39 mm. high, of which the calyx occupies 6.5 mm. 
Has 3 arms, and stem in plane of anal series. Median arm fairly stout, tapering, 
as long as the lateral arms, consisting chiefly of two long brachials, four or five 
times as long as wide, preceded by the short primibrach and followed by a third 
brachial shorter and narrowing to a point; segments of 1. ant. radial connected, 
with inferradial elongate quadrilateral. Lateral arms 2, one on each side, divid- 
ing on second primibrach into 2 rami, dichotomous, branching' somewhat un- 
equally at intervals of 3 or 4 brachials to abouC6 finials, the ramus next to the 
anal tube being the smallest. Stem long, slender, about three times the length 
of the crown, tapering gradually to a narrow distal end ; columnals in proximal 
part about i mm. long and wide, becoming longer with half the width distally. 
In form and proportions of the median arm this species differs strongly from the type, 
and resembles those of the associated species of Cremacrinus occurring in the same formation ; 
but the absence of a fourth arm and the median position of the stem clearly exclude it from 
