HETEROCRINIDAL 
II9 
Calceocrinus halli Ringueberg 
Plate eg, fig. ig 
Ringueberg, Ann. New York Acad. Sci., 4, 1889, p. 403, pi. 10, fig. 9. 
Type of the species which Ringueberg considered identical ■ with Hall’s 
original. The consolidated left basal, fused into a single triangular plate not 
touching the stem, is the dominant character in both, fully establishing their 
generic identity, and by reason of its exceptional width their specific identity also. 
Horizon and locality, same as last. 
Calceocrinus alleni Rowley 
Amer. Geol., 34, 1904, p. 275, pi. 16, figs. 30-33. 
Described from fragments of calyx only, which show only the probable generic characters. 
Bainbridge formation. Niagaran ; Ste. Genevieve County, Missouri. 
Calceocrinus nitidus Bather 
Plate eg, fig. 20 
Calceocrinus nitidus Bather, Crin. Goth, 1893, p. 91, pi. 3, figs. 1 17-122 . — Synchirocrinus anglicus Jaekel, 
Phylogenie und System, 1918, p. 86, figs. 81-83. 
I am illustrating this species from an unusually fine specimen in my collec- 
tion from England, in which the crown is more completely preserved than in 
the types. In the principal one of these the median arm has only 8 brachials 
remaining, whereas here they reach a total of 15. The arm is decidedly stouter 
and longer than those adjoining it, and has a graceful curvature parallel to 
the 6 visible axil-arms, of which only the outer or adanal ramules are seen, the 
main branches being entirely concealed underneath them. The species is re- 
markable for having only a single lateral primibrach, in which it differs from 
all others in the family known to me, with the exception of the singular English 
species herein described as Eiieheirocrinus anglicus. 
Although described from Gotland, C. nitidus is apparently the most common species of 
this genus in the English Silurian, as among my own material are no less tloan four good 
specimens, besides two casts from specimens in British collections, in all of which the char- 
acters are remarkably constant. One of these has the stem in place, but incomplete, for a 
distance of once and a half the length of the crown, which is closely recumbent upon it ; the 
columnals in the more distal portion have increased to 2 mm. in length for 3 mm. diameter. 
This species is undoubtedly the same form for which Jaekel in his Phylogenie und Sys- 
tem, 1918, has encumbered the literature with two useless synonyms as Synchirocrinus anglicus. 
Horizon and locality. Wenlockian, Silurian ; Gotland, Sweden, and Dudley, England. 
