LECANOCRINIDAE 1 33 



This is one of two rather abundant species in Gotland corresponding somewhat to 

 L. pusillus and L. pisiformis of the American Niagaran. They occur in different localities, 

 the present species being found in the vicinity of Wisby, in horizon d, whereas the other is 

 from the south of Gotland. This is of the type" of L. pusillus, having the same thick calyx 

 walls, and distinct though very fine granular ornamentation ; yet there is enough constant 

 difference to preclude its reference to that species. Its average size is nearer that of 

 L. pusillus, but it is otherwise not at all like that species ; nor does it represent a juvenile type, 

 the arms being heavy and well developed to the third bifurcation. There are 148 specimens 

 in the Riks Museum, of which 14 have more or less of the arms preserved. In these 14 there 

 are 40 complete rays, and with one exception they all have two primibrachs. Among this 

 large number of specimens are some interesting variations in the construction of the calyx 

 parallel to what is shown in our Tennessee species. These variations, shown on Plate II, 

 are chiefly in the development of the plates of the anal side, on which some of our most 

 important generic distinctions are based. 



Three of the specimens have an abnormal radianal ; one has RA unusually small and 

 triangular instead of quadrangular (fig. 8) ; one has RA in primitive position below r. post. R, 

 as in Clidochirus (fig. 9) ; while in the third the RA lies vertically below the anal x (fig. 10). 

 Nine specimens have no radianal at all (a Silurian Mespilocrinus), the space belonging to the 

 missing plate being filled up in different ways ; six of them have the posterior basal much 

 enlarged (fig. 11) ; two have the right posterior basal enlarged (fig. 12) ; while the remain- 

 ing one, not figured, is a deformed specimen with only four radials and two.basals. In three 

 specimens the large anal x is wanting; one having RA normal (fig. 13) is unlike any de- 

 scribed genus ; a second has RA in primitive position like Ichthyocrinns (fig. 14) ; and the 

 third is hopelessly malformed. In addition to these there is another specimen with normal 

 RA and anal x which has only three large radials completing the circlet, and a basal ring of 

 seven plates of varying size and form abutting upon the inf rabasals ; and besides these a 

 quadrangular plate (a sort of supernumerary RA) between the ring of basals and radials 

 to the right of the r. post. B (PL II, figs. 15a, b). 



In sufficiently energetic hands this little collection of abnormal Lecanocrini, although 

 from the same area and horizon, might form the basis of a choice assortment of new genera 

 and species, such as have sprung up in some of our rich American localities. Yet it is per- 

 fectly evident that they represent merely the variations of a single prolific species, either 

 reproductions of different- embryonic or larval stages, or mere sporadic malformations. 

 Figure 3 gives an inside view of the calyx, showing very plainly the triangular enlargement 

 of the axial canal. 



Types. Angelin's principal figure (Icon. Crin. Suec, pi. 22, fig. 25) is a restoration, 

 but the specimen on which it was based is refigufed on Plate II, figure 1. That and. all the 

 other specimens figured herein are in the Riks Museum, Stockholm. 



Horizon and locality. Silurian, Wenlock Group, horizon d; Wisby, Island of Gotland, 

 Sweden. 



Lecanocrinus facietatus (Angelin) 

 Plate II, figs. 16-21 



Cyrtidocrinus facietatus Angelin, Icon. Crin. Sueciae, 1878, p. 20, pi. 21, figs. 13-14(1. — Wachsmuth and 

 Springer, Revision Palaeocrinoidea, pt. I, 1879, p. 145. 



A small species. Crown subglobose, obtusely rounded or truncate below, 

 widest at top of I Ax; average height to width at that level about 1 to 1.1 ; at top 

 of RR, 1 to 1.3. Surface marked by small pits, producing a very fine network 

 usually not preserved in the specimens. Calyx plates thin. Maximum specimen 

 at I Ax, about 10 mm. high by 11 mm. wide; at RR, 8 mm. by 11; width at 

 column facet, 3.5 mm. 



