(he ^'■Clrripede^^ Lepidocoleus. G55 



and the scroml shell sliow certain narrow longitudinal de- 

 pressions, hut these are evidently due to compression. 



Another specimen (Pi. X. figs. 1-4) was in two pieces, 

 wiiich fitted together quite readily. The larger piece sliows 

 a column of eight plates and an impression of another plate, 

 and this is presunnibly the specimen represented by Cowper 

 Keed (1U08, pi. xii. fig. 9) in an inverted position, although 

 it is not easily recognised from the figure. The smaller 

 piece, which consists of two columns, each of four plates, is 

 evidently the third specimen mentioned by Cowper Reed. 

 These two pieces, then, together comprise twelve plates and 

 an impression of another in serial order, and these plates do 

 not appear to have been dis[)laced in any way, so the length 

 of the shell, which measures 21*7 mm., is probably the 

 correct length of the piece preserved, and its greatest 

 breadth is 50 mm. On the other side of the shell the 

 lowermost four plates are shown, but since they are mucli 

 flattened, they do not show well on the broad "fixed" margin; 

 but above these, in the middle of the specimen (PI. X. 

 fig. 2), the plates of the two series are seen to be in close 

 apposition with little or no alternation. On this same 

 side of the specimen, the lowermost three plates are broken 

 away towards the narrow "free^' margin, and, since the 

 fourth plate is entire, one can measure the degree of overlaj). 

 The fourth plate has a breadth of 4*7 mm., and a length of 

 2*7 mm., and the third plate overlaps this to the extent of 

 r2 mm., leaving 1*5 mm. exposed. The ornament of the 

 plates consists of fine growth-ridges comparatively wide- 

 spaced, numbering about four to a millimetre, and between 

 these are from five to six slightly finer ridges, which give to 

 the shell a peculiarly closely and regularly ridged appearance. 

 Although the main ridges are clearly seen on both specimens, 

 the finer ridges are well preserved only on this one, where 

 they are very clearly shown on the lowermost four plates 

 of the right-hand series ; an enlarged view is given of the 

 two lowest plates (PI. X. fig. 3). 



Comparison icith other species. — L, (jruycs is distinguished 

 from other species by its exceedingly fine and numerous 

 growth-ridges, but it would ajjpear to differ also from tiie 

 known Ordovician and Silurian species in the length of 

 tlu; shell and the number of plates. L. grnyce has at least 

 sixteen plates to an incomplete shell, which would have 

 measured at least 25 uim. L. jamesi (Hall & Whitfield), 

 from the Hudson River Group (Ordovician) of Cincinnati, 

 is said to have only fifteen plates in a complete shell, and 

 this has only a lengtii of about 12 mm., less than half 



