Bemarks- upon the Kaftkaskia Group. 41 



plate, and the upper side supports the tburth az^-gos plate. The third 

 azygos plate is supported below ui)on the first azygos plate, the right 

 inferior side joins the second azygos, the right superior the fourth azj^- 

 gos, the top the fifth azygos, the left side a second radial, and it corn- 

 ers with a first radial below. The fourth azygos plate reaches upon 

 one side the right anterior second radial, otherwise it is joined to az}'- 

 gos plates. The fifth az3^gos is bounded by azj-gos plates. The azy- 

 gos plates cover a convex ridge to the center of the vault, and termin- 

 ate in a small needle-like proboscis. 



Arms. — The arms are strong, simple, slightly convex upon the out- 

 er side, and flattened latterall}^ so as to fit close together. The first arm 

 plate is double the size of succeeding ones, this is followed by from two 

 to four wedge-shaped pieces in each arm, and above these there is a 

 double series of alternating wedge-shaped pieces. The furrow upon 

 the inner side of each arm is protected b^' a pinnule springing from 

 every plate upon each side of the arm. 



This species is distinguished from E. sparlarixs, which it most re- 

 sembles, chiefly by the number, form, and arrangement of the azj'gos 

 interradials, and b}- the shape of the left anterior first radial, though 

 it differs in minor details in nearly all parts of the body and arms. 



Locality. — This species is described from specimens in the collection 

 of Prof. A. G. Wetherb}', who discovered them in rocks of the age of 

 the Kaskaskia Group, in Pulaski county, Kentucky. 



Lepidesthes fokmosus, n. sp. (Plate VIII., fig. 4, magnified two 



diameters. 



[Ety. —Formosus, beautiful.] 



The general form of the bod}', judging from a single compressed 

 specimen, is subspheroidal or truncato-elliptical. Surface of the plates 

 smooth. 



Amhulacrol areas. — The ambulacral areas are somewhat lance- 

 elliptical in shape, and apparently suflSciently convex to preserve the 

 circular shape of the body. These areas are occupied by numerous 

 rhomboidal and irregularly hexagonal pieces, arranged in curved lines 

 crossing each other in quincuncial order, and imbricating downward. 

 The specimen shows eight plates, in each curved row, below the first 

 five, from the occular pieces. Ten rows of 8 plates each maj- be counted 

 in one ambulacral area of the specimen; the difference in width of the 

 area being compensated by a greater exposure of the surface of the plates 

 as we approach the middle ; some of the rows have nine plates, and it may 

 be that a better specimen will show more pieces in the central part of 



