Nov., 1918] Structure of A gelacrinites and Streptaster 63 



one quite large and composed of numerous very small plates. 

 Ovarian (anal) aperture situated subcentrally in the largest 

 inter-radial area." 



Streptaster vorticellatus Hall, 1866-72: "All arms sinistral. 

 Marginal portion of disc several ranges of minute squamiform 

 plates. Inner portion of disc occupied by five elevated sin- 

 istrally curved and closely coiled rays or arm grooves, the 

 curvature of each ray making about K a volution. Rays 

 composed of a double ray of lanceolate spatulate plates which 

 interlock at their upper ends to cover the arm grooves. The 

 plates forming the outer curvature of the rays are the longest 

 and inclined at a lower angle than those of the inner side. 

 The inner ends of the rays terminate in a solid pyramid formed 

 by the union of the two bifurcating or V-shaped plates and one 

 shield-shaped plate. Inter-radial areas very small, hardly 

 perceptible. Ovarian (anal) aperture minute, situated near 

 the bases of the postero-lateral rays." 



Streptaster septemhrachiatus Miller and Dyer, 1878: This 

 seems merely an example of duplication of parts, a seven rayed 

 specimen of the preceding species. I have a medusa which has 

 five radial canals instead of the usual four, but it could hardly 

 be called a new species. 



Agelacrinus warrenensis James, 1883, The Palaeontologist, 

 No. 7, p. 58, Plate II, Figs, 3, 3a. "Body circular, varying in 

 diameter from K to %. inches or more. Attached to the convex 

 valves of Strophomena (Rafinesquina) and probably other 

 foreign substances. The under side concave or otherwise 

 conforming to the surface grown upon. Disc composed of 

 squamiform plates overlapping inward from the periphery. 

 The plates of the outer margin very small and arranged in a 

 narrow rim all around the narrow plates taking their place 

 abruptly. About one line a little more inward the surface 

 becomes suddenly depressed, causing quite a sharp outward 

 ridge, in most cases all around, by the projecting edges of the 

 plates and then rises, gently at first, but abruptly nearer and to 

 the center forming a somewhat prominent dome. The rays 

 or arms nearly hidden by the imbricating plates in all the 

 specimens examined, but occasionally the arms are partly but 

 indistinctly shown as is the case in the figured specimen, etc. " 



Dr. Foerste doubts the validity of this species and considers 

 it merely a young A. cincimiatiensis . Fig. 27, Plate V, is the 



