LEPIDESTHKS. 421 



ercles and spines. The details of structure can be ascertained only with difficulty and not 

 with entire certainty. 



Ambulacral plates are small, about 3 mm. in width, and somewhat \vidT t han high. They 

 are polygonal, imbricating, with, on the exterior, pore-pairs situated in about the middle of each 

 plate. On the internal mold they are situated somewhat nearer the ventral border of the plat <- 

 (as in Lepidesthes extremis, Plate 71, fig. 2). The ambulacra! plates bear small tubercles simi- 

 lar to those of the interambulacral plates. It is difficult to be certain of the number, but there 

 are at least eight columns of ambulacral plates in an area. 



In the interambulacra there are apparently seven columns in an area, as stated by Wli id- 

 borne, and I confirmed this by observation. The plates are small, about 3 mm. in width and 

 height, and bear numerous small tubercles. Whidborne says these are minutely perforate. 

 This is doubtful, though in some of the impressions there seem to be traces of the impression 

 of a perforation. Such are not known otherwise in the genus. 



The spines are numerous, acicular, swollen at the base, and measure up to 5 mm. in Imntli. 

 The spines as far as seen are all essentially similar, and I saw no second series of smaller spines 

 as Whidborne thought. Of course, in any specimen some spines are smaller than others, but 

 I think that here there is no indication of two series as regards size. The impressions of a stout 

 lantern are present. 



Whidborne gives a very detailed discussion of this species, and, as he says, it fails to meet 

 entirely the requirements of the genus. The main difference is the apparently minutely per- 

 forate tubercles. It does have characters of Lepidesthes and would not fit in any other genus, 

 so that it seems best to leave it here. The chief interest in the species is that it is from the 

 Devonian, and is thus geologically older than any other known species of the genus, and also 

 it is from Great Britain, being the first of the genus described from that country. The speci- 

 men in general appearance resembles my figure of L. extremis, at least the internal mold does. 



Pilton Beds, Upper Devonian, North Devon, England, holotype, Museum of Practical 

 Geology Collection 7,160 and 7,161 (these being counterparts); and Croyde, England, in Mr. 

 Whidborne's collection. 



Lepidesthes spectabilis (Worthen and Miller). 

 Text-figs. 248-250. 



Ihjbochinus spectabilis Worthen and Miller, 1883, p. 332, Plate 31, figs. 5a-5d, 6, 7. 



llybochinm (without giving specific name) Duncan, 1889a, pp. 16-18. 



Lepidesihes spectabilis Keyes, 1895, p. 184; Klem, 1904, p. 26; Lambert and ThieYy, 1910, p. 123. 



Hybocchinus spectaJttilis Jackson, 189(5, p. 207. 



This species I have not seen, and its characters are somewhat ambiguous, as gathered from 

 the description and figures. In regard to the imbrication in this species, Worthen and Miller 



