INVERTEBRATES. 235 



ulose, tumid and angular plates, which are united by distinct 

 sutures. Base comparatively small, and apparently truncated 

 on a plane with the tumid portion of the subradial plates. 

 Subradial plates as wide as high, four of them pentagonal, and 

 one on the anal side hexagonal, there being no visible angle at 

 the middle of the base in any of them. First radials larger 

 than the subradial pieces, about twice as wide as long, penta- 

 gonal or subheptagonal, in consequence of the superior lateral 

 angles of some being truncate for the reception of small inter- 

 radials ; all broadly truncated and more or less concave above. 

 Second radials extremely short, but differing somewhat in 

 length, some of them eight or nine times as wide as long. 

 Third radials larger than the second, unequal in size, all wider 

 than high, and triangular in form. First anal plate smaller 

 than the subradials, a little narrower below than above, appa- 

 rently pentagonal in outline (the upper extremity is not dis- 

 tinctly seen in the specimen described), and extending some- 

 what above the summit of the first radials. 



Arms large, rounded and robust, apparently simple after the 

 division on the third radials, and composed each of a single 

 series of pieces, which are wider than long, and somewhat 

 wedge-shaped. Plates, below the second radials, remarkable 

 for their thickness and tumid angular character, though the 

 angles are not acute. On the subradials two of these ridges 

 pass from the middle to the base, nearly parallel to each other 

 (leaving a shallow furrow between), and one to each of the first 

 radial pieces above. On each first radial there are two similar 

 ridges or prominences, which diverge from near the upper side 

 to the base, so as to connect with those on the subradial pieces, 

 giving to each first radial a somewhat bilobate appearance. 



Our specimen of this species is too much distorted to enable us to give accu- 

 rate measurements, though the body below the arms seems to have been about 

 0.50 inch in height, and near 1.10 inches in breadth. It is more nearly related 

 to Oyatliocrinus sculptilis, Hall, than to any other species with which we are 



