204 



PALiEONTOLOGY OF NEW-YORK. 



594. 1. MACROSTYLOCRINUS ORNATUS (n. sp.). 



PL. XL VI. Fig. 4a -g. 



Body small, composed of three pelvic plates of moderate size, succeeded by five large costal 

 plates, three of which are heptagonal and two are hexagonal, having all truncated upper margins 

 on which rest the scapular plates, and to which succeeds in each series a single arm-plate ; a 

 single hexagonal or heptagonal interscapular plate is interposed between the scapular plates, 

 its lower oblique edges resting on the short oblique upper edges of the costal plates ; the inter- 

 scapular plate supports two small plates above it, which are succeeded by other small plates ; 

 each arm-plate supports upon its oblique upper edges a pair of arms, which diverge from each 

 other ; each arm in its lower part is formed of a single series of eight or nine plates, above 

 which it is composed of a double series slightly interlocking with each other ; surface of plates 

 of the body tuberculo-striate, the lower ones being marked with interrupted ridges or striee 

 with few tubercles, while the upper ones, or the scapular, interscapular and arm-plates, are 

 covered with minute tubercles, sometimes elongated in a direction from the centre to the upper 

 and lateral margins ; two or three of the lower simple joints of the arms are tuberculate or 

 crenulate on the upper margins, while the upper or double series of plates of the arms are 

 marked by distinct round or subangular tubercles along the centre. 



The body of this species is very prettily ornamented by elevated striee and tubercles, some- 

 what similar to the body of Thysanocrinus liliiformisj but more strongly, particularly in its 

 upper portion. The arms are very long and much diverging, destitute of fimbriae. The distin- 

 guishing feature of the arms is the simple series of plates in the lower part, with a double 

 series above ; which portion, in fragments, may be distinguished by the prominent node or 

 tubercle upon the back of each joint, with less prominent ones upon the sides. The column of 

 this species is entirely unknown, but it is probably round, with alternating thicker and thinner 

 joints, the margins in some parts probably nodulose. 



Fig. 4 a. The specimen described, showing the body and four of the arms, all broken off before 



reaching their termination. 

 Fig. 4 b. The structure as ascertained from the specimen 4 a. 



Fig. 4 c, d. Two costal plates enlarged, showing their striate and tuberculo-striate character. 

 Fig. 4 e. A pelvic plate enlarged, showing a striate surface only. 



Fig. 4 /. A plate from near the base of the arms, showing the tuberculo-crenate upper edge. 

 Fig. 4 g. Several joints from the upper part of the arms enlarged, showing the strong tubercle 



on the back of each plate, with smaller ones on each side. 



Position and locality. In the shale at Lockport. {Collection of Col. Jewett.) 



