I32 SMITHSONIAN INSTITUTION 



Lecanocrinus pusillus belongs to a more globose type than L. macropetalus, and differs 

 in the surface ornamentation. It may be considered as corresponding in a general way to 

 L. billingsi of the Gotland rocks, just as L. pisiformis does to L. facietatus. It has the same 

 thick calyx walls, so that specimens are rarely flattened. As compared with L. pisiformis it 

 has a lower and broader calyx, the crown not constricted at the primibrachs, larger infra- 

 basals and basals, and smaller radials. The broad and relatively low obtuse-angled anal plate, 

 shallow column facet, and thick calyx walls are plain and evident characters to distinguish it 

 from the species most likely to be encountered in the same region. There is some variation 

 in the protuberance of the infrabasals, this being quite marked in some specimens. The sur- 

 face ornament was evidently strong, as it is visually preserved on the specimens. In addition 

 to the enlarged view shown on Plate I, figure 4c, the surface markings may be seen with an 

 ordinary magnifier on two of the full figures <\b and 10 on the same plate. 



The species is a very characteristic fossil of the Niagaran shales at Waldron, Indiana, 

 and Newsom, Tennessee, but has not been found at Lockport, or other New York or Canada 

 localities. It is not so abundant as the species from the Brownsport limestone, and is rarely 

 found with any part of the arms attached. But a single specimen is known with the arms 

 complete, and that is the one figured by Hall in the nth Indiana Report, plate 15, figure 7, 

 and now in the New York State Museum (PI. I, figs. 3a, b). Another specimen in my col- 

 lection preserving the rays to IIBr t , also from Waldron, is an unusually elongate form, 

 (fig. 9) but has the characteristic surface ornamentation (not shown in the figure), and is 

 undoubtedly a variant of this species. One of Hall's type specimens (28th Rep., pi. 15, 

 fig. 5) had abnormally a second anal plate which he made a specific character ; his other speci- 

 men (his fig. 4) shows the usual form of the single plate, which I have found constant in 25 

 specimens from two localities. One of my specimens has an abnormal base, the proximal 

 ring being composed of three small infrabasals and one large plate which combines the func- 

 tions of both infrabasal and basal, there being but four of the latter. The column of the 

 perfect specimen is so very unusual for this genus as to be almost abnormal ; such extreme 

 contrast in the size of the alternating columnals I have not seen in any other species. 



Hall described this species originally under Cyathocrinus; but a few years afterwards 

 he saw its relation to his own genus and made the reference accordingly in the 28th Report. 



Types. The originals of the 28th Report, plate 15, figures 1-6, are in the American 

 Museum of Natural History, New York; that of the nth Indiana Report, plate 15, figure 7, 

 is in the New York State Museum. The other specimens figured are in the author's collection. 



Horizon and locality. Silurian, Waldron shales ; Waldron, Indiana, and Newsom, Ten- 

 nessee. Also rarely in the Laurel beds at St. Paul, Indiana. 



Lecanocrinus billingsi Angelin 

 Plate II, figs. 1-15 



Lecanocrinus billingsi Angelin, Icon. Crin. Sueciae, 1878, p. 12, pi. 22, fig. 25a. — Wachsmuth and 

 Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 40. 



A small species. Similar to L. pusillus, but in general the calyx is propor- 

 tionally lower and broader, the average of several specimens giving height to 

 width at I Ax of 1 to 1.4; at top of RR, 1 to 1.8. It is less rounded below, RR 

 shorter, and IBr proportionally longer; height of B to R to IBr, 2.5:2.7:1.2. 

 The arms are proportionally heavier, more rounded, longer and extending" higher 

 up before infolding. Column composed of short ossicles, increasing in length 

 but of uniform width, without alternation in either. Surface marked by fine 

 granular network. Maximum crown is 16 mm. total height by 10 mm. wide at 

 IAx; at RR, 5 mm. by 8.5 mm. ; width at column facet, 2.5 mm. 



