330 REPORT ON THE STATE CABINET. 



The specimen is so imperfect that it is not possible to give a full 

 description of parts ; the outer limits of the rays having been obscured 

 by scraping and the too free use of acids, before the specimen came under 

 my observation, so that the exact number of marginal and other plates 

 cannot be determined. This form differs, however, from all others 

 described or known, in the comparatively large marginal plates, the 

 triangular spaces at the base of the marginal ranges, and the single 

 series of ambulacral ossicula. It is possible that this last character may 

 prove to be of generic importance, could we obtain specimens sufficiently 

 well preserved to show these and other characters in a more perfect 

 manner. 



Geological Formation and Locality. — The specimen is from the Hudson 

 River group, Harpeth River, Davidson county, Tennessee. 



Pal^aster eucharis, n. s. 



PLATE IX. FIGS. 3, 3*, 3rt and 4. 



Body rather large ; the largest individual being one inch and seven-eighths 

 from the centre of the body to the extremities of the rays ; the whole 

 having a robust aspect; rays acutely pointed at the extremity. 

 Upper surface of rays composed of three ranges of large, highly con- 

 vex or tuberculiform plates which are nearly circular at the bases 

 of the rays, becoming quadrate and widened towards the extremi- 

 ties ; sepai-ated from each other in the lower part by numerous 

 minute plates or granules, which become fewer near the middle of 

 the ray, and disappear before reaching the extremity. The central 

 portion of the disc is occupied by an elevated pentagon, the angles 

 of which are formed by the abrupt termination of the central row of 

 plates of each ray : the whole composed of very minute, highly con- 

 vex plates, which vary in size, the larger ones pentagonally arranged. 

 The angles between the rays have a few small plates outside of the 

 outer ranges of tuberculose plates on the upper side, uniting with 

 the marginal plates below. Madreporiform tubercle distinct, situated 

 laterally at the bases of the outer range of large plates of two adja- 

 cent rays. Ventral surface having deep ambulacral grooves , bordered 

 by two ranges of strongly tuberculose plates ; the outer marginal 

 range consisting of twenty-seven or twenty-eight plates, besides a 

 large, round, terminal or axillary plate; the others are wider than 

 long in the basal portion of the ray, becoming gradually shorter 



