274 SMITHSONIAN INSTITUTION 



fully as good as Conrad's. He gave however a very good figure (Silurian System, pi. 17, 

 fig. 6), which affords a clear idea of the general form and proportions ; and this, added to one 

 more item mentioned in his brief description, enables us to recognize his species without any 

 doubt. That is : " the surface is marked by a faint, irregular ornamentation, not unlike 

 Cyathocrinus tuber culatus." 



M'Coy in 1854 referred the species to Conrad's genus, and gave a revised generic 

 description, in which some important additional characters are pointed out — notably the 

 absence of interradial plates. He also redescribed the species, giving a correct account of 

 the column, but otherwise furnishing no new information. Most of his lengthy description 

 is devoted to detailed measurements of various plates and " fingers," which unless given in 

 the form of relative proportions amount to nothing more than the description of parts of a 

 particular specimen. 



Angelin identified the species among the Swedish forms, with good reason as to one of 

 the specimens he figured (Icon. Crin. Suec, pi. 22, fig. 22), but not as to the other {ibid., 

 pi. 17, fig. 6) which is a fine example of his genus Clidochirus. 



I have copied Phillips's original figure (PI. XXXII, fig. 1), and along with it I have 

 given figures, both natural size and enlarged, of a specimen in my collection from the same 

 locality which in size and form is almost a counterpart of the type {ibid., figs. 2a, b, c). An 

 enlarged figure of one plate of this specimen (fig. 2d) shows the character of the ornamenta- 

 tion found on the English specimens. Several other specimens in my own collection and in 

 the British Museum, from the typical locality at Dudley, England, and having the charac- 

 teristic ornamentation (which scarcely appears in a drawing of natural size), show the small 

 variation in form that is found. The resultant of all these taken together is an elongate, 

 pyriform crown, in its proportions quite similar to that of /. laevis, but correspondingly dif- 

 ferent from the broadly spreading ovoid crown of /. corbis and /. gotlandicus. It is gener- 

 ally a more delicate form than I. laevis, the one large specimen from Gotland being very 

 much larger than any of the others. Besides this the surface ornament clearly differentiates 

 the two species. 



In addition to several views of Angelin's plate 22, figure 22, erroneous in showing pro- 

 jecting IBB like Clidochirus (see PI. XXXII, figs, ga-e herein), I have figured on the same 

 plate three other specimens of this species from Gotland with structural details still further 

 illustrating the surface characters. Of these figures na-,g~ are from Angelin's plate 9, 

 figure 17, referred by him to /. laevis, and figures 13a, b are from a specimen of unusual size, 

 much larger than the average of the English specimens. In all these it will be seen that 

 the base is quite uniform, and altogether different in its development from that of I. got- 

 landicus. They, and others which I have examined in English collections, have quite gener- 

 ally four secundibrachs all around, with occasional exceptions in some rays, mostly by way 

 of increase in number. I have therefore been somewhat puzzled over one of my specimens 

 from Dudley, which has only three secundibrachs in most of the rami, but has the pyriform 

 figure, well developed infrabasals, and fairly large basals of this species (PL XXXII, 

 fig. Ja). It seems to be a variant in the direction of I. gotlandicus, and this is confirmed by 

 the measured dimensions which give a proportion of height to width of 1 to 1.5. 



The specimen figured by John Kills * in 1762, and copied by Parkinson, 2 may perhaps 

 have been of this species. The figure is probably enlarged, although no mention is made of 

 this in the text, and the drawing of the basal parts of the fossil is uncertain. The locality is 

 given as Pyrton-Passage in Gloucestershire, where strata equivalent to the Wenlock are 

 exposed. . 



1 Philosophical Trans. Roy. Soc. London, vol. 52, pi. 13, Fig. B. 



"Organic Remains of a Former World, vol. 2, 1808, pi. 19, fig. 2 (reversed in copying). Also by 

 Quenstedt as Pentacrinus tuberculatus, Petref. Dentschl., 1876, taf. 97, fig. 7. 



