LKCANOCRINIDAE 185, 



I have figured under this species a peculiarly abnormal specimen, which otherwise could 

 not be assigned to any known genus (PI. XI, figs, \6a-c). In general appearance of the arms 

 and calyx it is similar ; and if we treat the lower plate in the right posterior ray as the radianal 

 separated from the anal and developed in its primitive position, while the anal plate is crowded 

 upward beyond the level of the radials, the structure may be consistently interpreted. We 

 have already seen similar abnormalities under Lecanocrinus. 



Types. In the Riks Museum. 



Horizon and locality. Silurian, Wenlock Group, horizon /; Follingbo, Island of Gotland. 



Pycnosaccus calyculus (Hall) 

 Plate XIII, figs. 6-9 ■ 



Lecanocrinus caliculus Hall, Nat. Hist. New York, Pal., II, 1852, p. 203, pi. 46, figs. 3a, b. — Beyrich, 

 Monatsber. Akad. Wiss. Berlin, Feb., 1871, p. 46 (Transl. in Ann. and Mag. Nat. Hist., (4) VII, 

 p. 404. 



Lecanocrinus calyculus ? Wachsmuth and Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 40. 



Lecanocrinus waukoma Weller (part) [not Hall], Bull. IV, Chicago Acad. Sci., pt. 1, 1900, p. 148, 

 pi. IS, fig. 11 (not figs. 6-10). 



A small species ; with calyx evenly curved, and not marked by any ridges or 

 pits, but perfectly smooth. It has a wide anal plate slightly rounded distally, 

 projecting somewhat above the line of radials, and in that respect resembling 

 Lecanocrinus, under which it was described. But the arms, though wide, are 

 distinctly rounded and not abutting, thus leaving open interbrachial spaces 

 which could not have been occupied by any plates suturally united to the rays, 

 but only by the perisomic integument characteristic of this genus. It has fairly 

 large IBB; IBr 2; IIBr 2 or 3. Arms well rounded. Column strong at the 

 calyx, with well rounded nodals and short internodals, and a very gradual taper 

 distally. 



This species was described by Hall from a calyx only, which he erroneously states was 

 from the shales at Lockport, New York. His specimen (PI. XIII, fig. 6) has all the appear- 

 ance of a limestone fossil, and this is confirmed by the discovery of my two specimens of pre- 

 cisely the same appearance figured along with it. They are derived from the upper Niagaran 

 (Lockport) limestone, above the shales — a horizon perhaps equivalent to the Racine dolomite 

 of the western Silurian. The fine specimen with arms and stem supplies the details which 

 were unknown to Hall ; while somewhat less spreading in the calyx, it agrees perfectly with 

 the other two in the relative proportions of the basal and radial plates. 



The specimen referred by Weller to Lecanocrinus waukoma, from the dolomite of 

 Chicago, Plate XIII, figures ga, b, is probably a massive variety of this species. 



Types. Hall's figure 3a is in the American Museum of Natural History, New York. 

 The other specimens now figured are in the author's collection. 



Horizon and locality. Silurian, Niagaran, Lockport limestone ; Lockport, New York. 

 Racine dolomite, Chicago, Illinois. 



