MLS OF THE F,rRLIN(, TON' UROUP. 473 



GRAXATOCKINUS XORWOODI, O. and S. (sp.) 



PL 9, Fig. 2. 



Pentremilts Xoncoodi, OWEX aud SHCMARD, 1850. Jour. Acad. Xat. Sci., Phila., 2d series. Vol. 2. p. 

 64, PL 7. Fig. 13. (1852,) GeoL Survey, Iowa, Wig. and ilinn., p. 591. PL 5 A, Fig. 13. 



GEXUS PALJECHIXUS, McCoy. 

 PAL-EfHixrs GRACILIS, M. and W. 



PL 10, Fig. 2. 

 Pal&rhinut graciKs, MEEK and \TORTHKS. Proceed. Acad. Xat. Sci., Phila.. 1869, p. 83. 



BODY small, and apparently oval or subglobose. Inter- 

 ambulacral areas a little convex. Tnterambnlacral plates 

 in seven rows at the middle, but apparently only the mar- 

 ginal rows of pentagonal pieces are continued to the upper 

 and lower extremities of the areas, the intermediate hexag- 

 onal pieces running out at various distances between the mid- 

 dle and the ends of the areas; thickness of each about half 

 the breadth of the largest; all ornamented with closely set 

 granules, of which 25 to 30 may be counted on each of the 

 larger pieces. Ambulacra! areas slightly convex, and equal- 

 ing in breadth the first and second rows of interambulacral 

 plates on each side, composed of very short pieces, which 

 are a little thinner than the interanibulacral plates, and 

 about three times as wide as long, the widest part of every 

 alternate one being at the outer end, which is received into 

 a little sinus in the adjacent marginal interambulacral plate 

 (there being generally three of these little sinuses to each 

 of these plates), while the intermediate pieces usually wedge 

 out rather abruptly before quite reaching the lateral mar- 

 gins ; the two pores at the outer end of each piece arranged 

 so as to form two zigzag or undulating rows along the lat- 

 teral margins of each ambulacra! area; surface of the Avhole 

 series occupied by granules of the same size as those of the 

 interambulacral plates. 



Entire dimensions unknown : greatest breadth of inter- 



-61 



