432 ROBERT TRACY JACKSON ON ECHINI. 



* Lepidesthes caledonica sp. nov. 

 Plate 72, figs. 3-10. 



In the British Museum and in the Museum of Practical Geology there are a number of 

 small slabs bearing isolated plates of Lepidesthes from Roscobie, Scotland. Excepting the 

 Lepidesthes devonicans from the Devonian, this is the first case of Lepidesthes reported from 

 Great Britain. The number of columns of plates in an area cannot be given, but there is 

 enough detail to warrant considering it distinct from any other known species. 



Ambulacral plates are low and wide. The surface of the plates, not counting the beveled 

 edges, measures about 2.5 mm. in width by 1.5 mm. in height. The ambulacral plates are 

 strongly imbricating adorally and laterally beveled under the adradials. The plates figured 

 show the dorsal and lateral beveled edges which respectively would underlie the adoral border 

 of the next ambulacral plate dorsally, or the left adambulacral plates of an interambulacral 

 area (compare text-figs. 32, 33, p. 75). The pore-pairs are in peripodia, lying to the right of 

 the centre of the plates as figured. On the surface of each plate there are about five to eight 

 small secondary tubercles. In one of the specimens four columns of ambulacral plates can be 

 counted in place, indicating that there were at least that number in an area. The interambul- 

 acral plates are thin, scale-like, rounded in outline, and imbricate strongly dorsally, as indicated 

 by the wide adoral bevel which would underlie the dorsal border of the next adjacent plate 

 ventrally. The surface of the plates bears numerous small secondary tubercles. Dissociated 

 small secondary spines occur with the plates. These are slender, tapering, expanded at the 

 base, vertically finely striate, and measure from 1.8 to 2 mm. in length. A number of dental 

 pyramids occur with the specimens. These are wide-angled, with a moderately deep foramen 

 magnum. As seen from the interior, the pyramid figured shows part of a grooved tooth in 

 place. Complete teeth seen from the interior and with the tips intact show that the teeth were 

 grooved, as shown by specimens in the British and Jermyn St. Museums. In side view, the 

 pyramids show plicate ridges for the attachment of interpyramidal muscles. 



Lower Carboniferous Limestone, Roscobie, Dumforline, Fifeshire, Scotland, British 

 Museum Collection E 10,699 to E 10,723, of which the holotype is E 10,710, the other speci- 

 mens being paratypes. Additional paratypes from Roscobie, in the Museum of Practical 

 Geology Collection 16,308 and 16,309. 



PHOLIDOCIDARIS Meek and Worthen. 



Pholidocidarui Meek and Worthen, 1869, p. 78; Loven, 1874, p. 40; Duncan, 1889a, p. 18; Jackson, 

 1896, pp. 210, 241; Tornquist, 1897, p. 765; Klem, 1904, p. 22; Lambert and Thiery, 1910, p. 123. 

 Protocidaris Whidborne, 1898, p. 202. 

 Echinocystis (pars) Lambert and Thiery, 1910, p. 118. 



