FOSSIL CRINOIDS. 153 



extremities. Proboscis large and strong, extending at least two and a half 

 inches above the first radial plates. Surface of subradials (BB) each marked 

 by two strong folds extending from the center to the upper sloping margins, 

 those of two adjacent plates meeting corresponding elevations on the two 

 lateral sloping margins of the first radial plates; these, uniting just below the 

 upper truncate margin of the plate, give it a strong'y thickened upper edge, 

 upon which the second radial (IBr) rests; less conspicuous folds or elevations 

 mark the other plates; and the entire surface is marked by sharp, slender, 

 radiating striae." 



It should be further stated that a similar strong fold to that described on 

 the basals passes horizontally from radial to radial, at the level of the radial 

 facets, giving a well defined, deep, triangular depression where the angles of a 

 basal and two radials meet; the ridge passing downwards from basals to infra- 

 basals spreads out gradually to the lower margin of the latter, where the base 

 is evenly circular; thus the depressions directly below the radials, over the inter- 

 basal sutures, are elongate diamond .shaped. The word "radiating," used in 

 describing the .slender striae, is misleading; they are parallel, following the 

 large ridges like flutingson a column. Primibrachs 1 ; radial facets facing nearly 

 vertical. 



This is an elongate form, higher than wide, and in this respect in marked 

 contrast with the last species. In a medium sized specimen the height of calyx 

 to greatest width at the bottom of the radial facets is as 1.1 to 1, with a very 

 uniform spread from base of 1 to 3, and above that some contraction to the 

 upper margin of radials. There is a marked difference in these proportions 

 between old and young specimens, the former being more elongate and slender 

 than above stated, while in very mature ones the width will equal, or exceed, 

 the height. This applies to some other characters as well : — In the young the 

 brachials are very elongate and slender, with the dice-box shape strongh' in 

 evidence (PI. IV, figs. 4, 5, 6), while in the older the brachials have filled out 

 until they are as wide as long, and about cylindrical (figs. 1, 2). The actual 

 length of the brachials in Fig. 4 is about the same as in those of Fig. 1 at their 

 longest side; the growth has been in width. This is the rule in the growing 

 Crinoid, as shown in the j'oung Comatulids and other cases, which I have pointed 

 out heretofore. Also the striation along the ridges is much sharper in the 

 young, and obscure in mature specimens like Fig. 1 . I have upwards of twenty 

 specimens of this species, in various stages of growth, in which these progressive 



' Uinlacriiius. Mem. Mus. Comp. Zool., Vol. XXV, No. 1, p. 03. 



