264 PROCEEDINGS OF THE ACADEMY OP [1879. 



B. Subgenus PYCNOSACCUS Angelin. 

 1878. Iconogr. Crinoid, p. 13. 



The distinction between Pycnosaccus and Lecanocrinus seems 

 to us scarcely sufficient to warrant a full generic separation. The 

 two agree in all essential features, except that the former, accord- 

 ing to description, has two primary radials instead of three, and 

 that the plates of the calyx are ornamented by radiating ridges, 

 such as are frequently found in Barycrinus. Even in that genus, 

 the ornamentation is not constant, and at the most is a ver}- un- 

 reliable character. In L. Rozmeri Schultze, which has entirely 

 smooth plates, we find in two rays only two primary radials as in 

 Pycnosaccus. It is very significant that if we consider the first 

 and second radials of Lecanocrinus as one plate, we obtain ex- 

 actly the proportions of the first radial in Pycnosaccus, which in 

 our opinion here replaces the first and second radials, while the 

 bifurcating second radial of Pycnosaccus actually represents the 

 third radial of Lecanocrinus. Form of body, arrangement of the 

 anal plates, and construction and folding of the arms precisely as 

 in Lecanocrinus, only that the arm plates are slightly higher. 



1878. Pycnosaccus (?) costatus Angelin. Iconogr. Crinoid, p. 14, pi. 15, fig. 13 

 Upper Silur. Gotland, Swed. 



(This species belongs probably to the Cyathocrinidse (?) ). 



1878. Pycnosaccus nodulosus Angelin. Iconogr. Crinoid., p. 14, pi. 15, figs. 12, 



14, and pi. 28, fig. 29. Upper Silur. Gotland, Swed. 

 1840. Pycnosaccus scrobiculatus Hisinger. (Cyathocrinites scrobiculatus(T)). 



Leth. Suec. Supplem. ii. p. 6, pi. 39, figs. 4 a-c ; also 1878, Angelin. 



Iconogr. Crinoid., p. 14, pi. 15, figs. 10, 11. Upper Silur. Gotland, Swed. 



6. MESPILOCRINUS De Koninck & Lehon. 



1853. Mespilocrinus, de Kon. & Lehon. Recher. s. les Crin. Carb. Belg.> 



p. 111. 

 1836. Young Poteriocrinus, Phillips. Geol. Yorksh., vol. ii. p. 205. 

 1866. Lecanocrinus, Schultze. Echinod. Eifl. Kalk., p. 40. 

 1859. Mespilocrinus, Hall. Supplem. Iowa Geol. Rep., p. 69. 



General form of body with arms, globular to pyriform, very 

 small. Calj'x bilateral, though apparently unsymmetrical on ac- 

 count of the dextrorse arrangement of the arms. 



Underbasals three, unequal; one quadrangular, the other two 

 larger and pentangular. Basals five; four of them equal, the fifth 

 larger and hexagonal, its upper face parallel with the lower. Ra- 

 dials three by five, the first forming part of the basal cup. Sec- 



