366 SMITHSONIAN INSTITUTION 



Eutaxocrinus whiteavesi n. sp. 



Plate XLIX, figs. 1-7 



Taxocrinus lobatus var. Whiteaves (not Hall), Contrib. Canadian Palaeontology, I, pt. 2, 1889, p. 94, 

 pi. 12, fig. 1 (Adv. Sheets, 1887, p. 94, pi. 12, fig. 1). 



A small species. Crown elongate, turbinate, spreading to about the level of 

 first IVBr, where the arms infold; height to width at that level about 1.5 to 1 ; 

 of calyx at top of I Ax, 1 to 1.2; spread from base, 1 to 2, with nearly straight 

 sides. Arms strong, broadly rounded below, diminishing rapidly with each 

 bifurcation, and lying close together but not abutting; lateral margins of brach- 

 ials angular or sinuous, bent sharply outward in wing-like projections fring- 

 ing the arms. Sutures strongly arcuate. Surface smooth. Crown of average 

 specimen 23 mm. high by 15 wide; base, 4 mm. 



IBB low, slightly exposed beyond the column, or entirely covered. BB 

 small, with obtuse distal angles; post. B broad, socket for anal tube slightly 

 to the right. Anal tube not preserved intact, but evidently small, composed 

 of elong'ate plates leaving considerable space chiefly at left side. RR large, 

 twice as wide as high, without any shoulders for support of iBr; IBr of similar 

 proportions, widening upward leaving very narrow iBr spaces which are bor- 

 dered on either side by the abruptly upturned edges of these and following 

 brachials. IIBr usually 3, rarely 4, or 2; height to width 1 to 2.5; IIIBr about 

 the same, with 7 to 12 plates in outer divisions, and 4 or 5 in the inner; higher 

 orders of brachials relatively narrower, with four to five bifurcations before 

 infolding. No iBr, but spaces at primary and secondary axils evidently filled by 

 perisome. Column large, flush with IBB ; tapering slightly for a short distance ; 

 a few proximal columnals are thin and below these the alternate ossicles become 

 longer-, rounded and projecting. 



The name of this species is proposed in memory of Dr. J. F. Whiteaves, the long-time 

 paleontologist of the Geological Survey of Canada, who first figured and described a speci- 

 men of it as Taxocrinus lobatus of Hall, a species which is clearly distinct by reason of its 

 3 primibrachs, 4 or more secundibrachs, widely divergent arms and other details. In the 

 wing-like fringe along the margins of the rays this species is distinguished from any other 

 Taxocrinoid, the structure being entirely different from the strong lateral buttresses in forms 

 like Protaxocrinus hiterbrachiatus, but similar to that found in Synaptocrinus nuntius of the 

 Ichthyocrinidae. 



There is in this species a considerable tendency to abnormal structures, several of which 

 are illustrated on Plate XLIX. In figure 56 there are small intercalated plates around the 

 posterior basal ; figure 6 has but one plate below the axillary in the left posterior ray, and 

 only the axillary in the right. Figures "ja-e are from a finely preserved specimen in a peculiar 

 condition which is well shown by the diagram ; it has but four rays, the right posterior being 

 entirely wanting and represented only by the three small plates shown in figure yc. Only 

 the posterior ray is normal, the other three having but one primibrach, the axillary ; and four 

 of the basals are of unusual shapes and sizes. In figure 4 exceptionally most of the rays 

 have 4 IIBr. The shape of the posterior basal and the position of the tube-socket are. variable, 

 but the upper margin of the plate is deeply curved toward the interior. 



