ICHTHYOCRINIDAE 297 



in young specimens. IIBr 3 or 4; IIIBr 5 to 7 or more; one more bifurcation 

 visible before infolding; arms not tapering rapidly above IIBr. Column large; 

 proximal columnals as wide as the base, thin, diminishing somewhat in width 

 downward and gradually changing to longer ossicles of about equal length. 



Angelin's specific description is but little more definite than the generic diagnosis. The 

 latter calls for four anal plates ; the former, more correctly, for three. The surface ornament 

 is the only other point mentioned, and this is important because somewhat different from that 

 of Ichthyocrinus. There it is produced by means of small raised granules, or pustules, scat- 

 tered over the surface, which by confluence become ridges in some places. Here the process 

 is reversed, and we have depressions instead of elevations, producing pits and grooves. The 

 description was based upon a single specimen from bed c at Wisby {op. cit., pi. 22, fig. 23), 

 imperfect at the base, which Angelin restored in his figure without taking any account of 

 inf rabasals. At the same time he figured on plate 17, figure 6, a weathered specimen also from 

 Wisby (bed d), with stem attached, which showed the prominent inf rabasals and very large 

 basals of the genus; but he did not recognize its relationship, and labeled it Ichthyocrinus 

 pyriformis. I have given a new figure of this specimen in the same view as Angelin's, 

 together with a view of the anal side, which Mr. Liljevall has since cleaned, showing the 

 lower part of the calyx, and the base detached from the stem (PI. XXXVII, figs. 3a, b). 



I also give an accurate drawing of the type specimen, showing just what is preserved at 

 the base, with its relation to the missing parts indicated. Inspection of these figures leaves 

 no doubt as to where Angelin's plate 17, figure 6 belongs. It is as stated a weathered speci- 

 men, and the surface markings are not preserved. These are well shown in the type specimen, 

 but still better upon a young specimen from the same locality and horizon, figure 2 on Plate 

 XXXVII. The change from scattered pits in the lower part to parallel longitudinal wrinkles 

 on the higher brachials is very distinct ; the small specimen also shows very plainly the exact 

 construction of the proximal columnals, and how they differ from those of Ichthyocrinus. 

 These three specimens give a very intelligible representation of the species, which seems well 

 characterized by them. 



There is, however, in addition to these a very large specimen from Tofta (horizon d) 

 showing such a great development in size that it may possibly belong to a different species 

 (PI. XXXVII, figs. 5a, b, c). It is fully twice as large as any of those before mentioned, 

 and has some tendency to angularity on the distal portion of the higher brachials. It shows 

 no surface ornament, but as it is a weathered specimen this may be due to erosion. It has all 

 the appearance of a very mature individual, and might readily be considered merely as such, 

 if it were not for the fact that there are in the Riks Museum at Stockholm, from the same 

 horizon at Wisby, two crushed fragments of specimens even larger than this, which show the 

 same tendency to angularity in the higher brachials ; but they also show, very plainly, the 

 surface markings characteristic of the type specimen (PL XXXVII, figs. 4a, b). On the 

 whole it seems difficult to point out any difference between these larger specimens and the 

 others which may not be due to individual growth or condition of preservation; and the 

 fact that there are three specimens of this size would rather indicate that the habitus of the 

 species is large, and that the type was probably undersized. 



Type. Riks Museum ; Stockholm, Sweden. 



Horizon and locality. Silurian, Wenlock group, horizons c, d; Wisby and Tofta, Island of 

 Gotland. 



