383 Bulletin 5 113 



21. An imperfect body of a crinoid animal, Encrinite of Authors; the 

 fragment is about one half of the inferior portion of the body, from which 

 the following description is made out, taking into view the whole circum- 

 ference. The plates composing the first costal series, (Miller) five in 

 number, are longitudinally pentangular, much curved inwards towards 

 the base to join the first roluniar joint, or perhaps the pelvis ; at which 

 part the plate is narrow, being about one-ninth of an inch, whilst the 

 other sides are nearly three-tenths of an inch each, the superior ones 

 being somewhat longer than the others; 'Ocv^ second costal plates, (Miller) 

 five in number, are transversely pentangular, the superior joint being 

 long, the lateral ones shortest, the former being one-half an inch in length, 

 the latter 3-20, and the inferior sides which articulate to the segments of 

 the pelvis, somewhat less than 3-10 of an inch ; the margins of the first 

 costal joints, as well as the superior margins of the segments of the pel- 

 vis, are armed with a few tubercles, some of which seem to have been 

 perforated ; all the superior pieces are wanting in our specimen, but the 

 truncated surface, on which \!h.& scaptilars (Miller) rested, is of a pentago- 

 nal oittline, and composed of a series of horizontal equilateral triangles, 

 two to each side, which are separated on each side from the adjacent 

 pairs by a deep groove, which corresponds, and is nearlj^ at right angles 

 with tlie exterior sutures, which join the first costal joints to each other ; 

 these triangular surfaces, are also separated from the exterior edge by two 

 grooves, which are crenated, and inclose an oblong foramina between 

 them ; a single intercostal plate occurs, interposed between two of the se- 

 cond costals, it is of an oblong hexagonal form, its base resting upon the 

 extremity of a. segment of the fii'st costals, which is truncated to receive 

 it, the superior portion of this plate is much bent inward towards the ab- 

 dominal cavity, its tip is quadrate and concave. 



The whole exterior surface of this reliquium, with the exception of the 

 tubercles, and sutural impressed lines, is plain and equable. 



If we have not mistaken the pieces of this imperfect specimen the pel- 

 vis is wanting, but the cavity in which it existed, must have been about 

 3-20 of an inch in diameter. 



The plate-like form of the ossicula, and their mode of articulation with 

 each other, by an extension horizontally inwards, as we have described 

 above, in the case of those plates which we have considered as the second 

 costals, seem to indicate, that this species ought to be referred to the se- 



[jFoot note, page i^o] . 

 cond division of the Crinoidea, or Seniiarticnlata of Miller. It certainly, 

 however, cannot be at all referred to Poteriocrinites, the only genus 

 which that author has framed in the division of the family. We refrain 

 from distinguishing it by a name either generic or .specific, until other 

 specimens can be obtained, in which the characters are less equivocal. 



We have two second costal plates, which made part of distinct individuals, 

 larger than the above described one. Of the.se the surface of one is per- 

 fectly glabrous, whilst that of the other has light orbicular indentation in- 

 .stead of tubercles ; a third very sinall one is perfectly smooth like the first, 

 and doubtless formed part of the body of a 3'oung individual. 



Another plate found near the same spot with the above, is of a some- 

 what triangular form exteriorly, or rather like the face of a truncated py- 

 ramid, of which the middle of the summit is a little produced in the form 

 of a right angle, thus offering a scollop on each side of the apex for the 

 adaptation of superior ossiculse. On divesting it carefully of its extra- 

 neous matrix, we discovered that it was readily adjusted by its base to the 



[Long's Expedition to the Rocky Mountains, Vol. I, 1823]. 



