280 SMITHSONIAN INSTITUTION 



is a fairly good copy of it, and his ijb a reconstruction of 17a with arms closed and a stem 

 added from Hall's figure 2a. It is by the figure 2b that the species has been known to 

 paleontologists the world over, rather than by Conrad's. It is therefore particularly unfor- 

 tunate that neither the type specimen of Conrad, nor the original of this much-quoted and 

 classic figure by Hall, can now be found after the most careful personal search and extensive 

 inquiry. 



The latter specimen was supposed to be in the American Museum of Natural History, 

 where the originals of Hall's 2b and 2c are, together with the beautiful specimen now first 

 figured by me (PI. XXXIII, figs. 30, b), all being from the original collection of Professor 

 Hall. It is so stated in Whitfield and Hovey's List of Types, 1 but an examination of all the 

 specimens of this species in the collection has failed to discover it. Hall at the end of his 

 description (Palaeontology of New York, vol. 2, p. 196) credits all the specimens figured by 

 him to the State collection and the collection of Col. Jewett. This specimen cannot be found 

 at Albany, and is not claimed in the List of Types published by the State Museum 2 in 1903. 

 Learning that a part of Col. Jewett's collection was acquired by Cornell University, I 

 also sought for it there, equally without success. 



No better fortune has attended the search for Conrad's type. It was supposed to be in 

 the collection of the Philadelphia Academy of Natural Science, and may in fact be there 

 buried out of sight, but neither the specimen nor any trace or record of it can be found. 

 As some of the specimens used by Conrad in various descriptions are known to have been 

 obtained from Hall, it was thought this one might be in some of the collections formerly 

 controlled by him ; but a careful search both at Albany and New York has failed to afford any 

 information. There still remained a second large private collection of Professor Hall addi- 

 tional to that acquired by the American Museum, stored at Albany until recently, when it 

 was purchased by the University of Chicago. Inspection of this material, thanks to the 

 courtesy of Dr. Weller, resulted in the discovery of some plaster casts from the original of 

 the figure of 1843, such as Hall was accustomed to preserve from specimens borrowed from 

 private owners. 



As this information was not obtained until after the plates for this work had been pre- 

 pared, I must refer again to Hall's two figures of the specimen above cited in order to point 

 out some inaccuracies which apparently contradict the specific diagnosis. The earlier figure 

 is a rather rough sketch showing the general form but not the definite arrangement of plates. 

 That of 1852 in the Palaeontology of New York, volume 2, plate 43, figure 2a, is an artistic 

 picture but faulty as to essential details ; it shows five secundibrachs in most of the rays, and 

 all the arms uniformly simple beyond the third bifurcation, whereas in the cast the secundi- 

 brachs are the usual four, and there is a fourth bifurcation in some of the rami. The cast also 

 shows very clearly the presence of the radianal at the base of the right posterior ray, while 

 in the drawing that ray is not different from the others. 



I have endeavored to give as complete a representation as possible of the typical species, 

 in all stages. The specimen figured by me on Plate XXXIII, figures 3a, b, now in the Amer- 

 ican Museum of Natural History, is the finest one of this or any other species of the genus 

 that I have seen. Except for a little foreshortening and lateral bending of the infolded arms, 

 it is absolutely rotund and perfect. The original of figure 13 on the same plate is the largest 

 known specimen; it is from Grimsby, Ontario, and belongs to the magnificent collection of 

 Silurian and Devonian fossils brought together by Sir Edmund Walker of Toronto, Canada, 

 and now through his liberality a part of the Museum of the University of Toronto. It is a 

 very mature specimen, with six bifurcations in some rays ; and owing to age and wear the 

 sinuous sutures have almost disappeared from the lower part. In striking contrast to this are 

 figures 7 and 8, which are interesting examples of the young stage ; the juvenile characters 



1 Bull. Amer. Mus. Nat. Hist., Vol. II, pt. 2, 1899, p. 92 

 ! Bull. 65 New York State Museum, p. 71. 



