LEPIDESTHES. 423 



*Lepidesthe3 coreyi Meek and Worthen. 

 Plate 66, figs. 8-10; Plate 68, figs. 18-22. 



Lepidesthcs coreyi Meek and Worthen, 186Sa, p. 524, text-fig. A on p. 525; 1873, Plate 16, figs. 2a, 2b; 



A. Agassiz, 1874, pp. 648, 649, text-fig. 4; Trautschold, 1879, p. 9; Keyes, 1895, p. 184; Jackson, 



1896, p. 209; Kleni, 1904, p. 25; Lambert and Thiery, 1910, p. 123. 

 Lepidesthcs corveyi (by clerical error) Trautschold, 1879, pp. 8, 9. 



This species is known from several well preserved specimens, including the type. Test 

 obovate, with ambitus dorsal to the mid-zone, a very unusual character in Echini (p. 32). The 

 holotype (Plate 66, figs. 9, 10) is imperfect dorsally, but the estimated height is about 45 mm. 

 The width is 51 mm., but this is exaggerated, due to lateral compression. The ambulacra at 

 the mid-zone measure 12 to 13 mm. in width and the interambulacra 8.5 to 9 mm. in width. 

 Mr. Braun's specimen (Plate 66, fig. 8) measures 57 mm. in height and 55 mm. in width at 

 the ambitus, but this measurement as in the type is affected by lateral compression; the 

 ambulacra measure 17 mm. in width and the interambulacra 10 to 11 mm. in width. Several 

 other specimens measured give about the same proportionate measurements. 



The ambulacra are wide, with, in each area at the mid-zone (Plate 68, fig. 18), ten or 

 exceptionally twelve columns of plates, which are rather low, wide hexagons, bearing pore-pairs 

 slightly above the center of each plate and also a little nearer the next adjacent interambula- 

 crum than the middle line of each plate. 



The interambulacra are narrower than the ambulacra, with six columns of plates in an 

 area at or above the mid-zone. Meek and Worthen speak of there being six or seven columns 

 of interambulacral plates, but I have not observed a seventh in any specimen of this species. 

 The plates are rounded on the suture lines, and imbricate strongly aborally and from the center 

 outward and over the ambulacrals on the adradial sutures. In the Freiburg i. B. specimen, 

 the primordial interambulacral plate is in place in the basicoronal row. There are two plates 

 in the second row and three in the third row, the fourth, fifth, and sixth columns coming in 

 later, at intervals, and the sixth originating usually above the mid-zone. In the type, however, 



(Plate 66, fig. 10), the sixth column in area A originates below the mid-zone. Ambulacral and 



interambulacral plates alike bear small secondary tubercles and spines about 1 mm. in length 



(Plate 68, figs. 19-21). The peristome, apical disc, and periproct are unknown in this species. 



In the Freiburg specimen there are five dental pyramids in place (Plate 68, fig. 22), similar to 



those of Lepidesthcs forrnosa. This species is the type of the genus. 



Keokuk Group, Lower Carboniferous, Crawfordsville, Indiana, University of Michigan 



Collection, holotype, no. 149; and another larger specimen, no. 150 of the same collection; 



F. Braun Collection; Museum of Comparative Zoology Collection, two specimens, nos. 3,173, 



