﻿IIOMALONOTUS. 



I 15 



which lies at a lower level than the hotly of the ring, and is often quite covered in the 

 act of bending (see fig. 1). The hinder rings gradually decrease in width towards the 

 tail, but very slowly so. 



The tail at its origin is rather less than three fourths as wide as the base of the cara- 

 pace. It is highly convex, trigonal, but with the front so much arched forward as to 

 give a sub-rhomboidal shape to the whole. The width and length are equal ; the axis, 

 more than one third the whole width, is convex above and highly prominent behind. 

 It extends nearly to the pointed tip, and is annulated for the greater part of its length 

 by ten or eleven rings, bent forward a little in the middle. The front furrow is sharper 

 than the rest, and is continuous with its pleural groove ; the others diverge more or 

 less from the corresponding axal furrows, and divide the lateral lobes into fewer than ten 

 or eleven rings, seldom more than eight ribs being visible on the sides. These do not 

 quite reach the margin, which is curved down and vertical, and is not produced or at 

 all flattened. The apiculus in most cases is but short ; its difference in length may 

 indicate the sex. 



The cornea of the eye has never yet been described for this genus, which is generally 

 supposed to have hiant or hollow eyes, i. e. with so thin a cornea that it is not preserved. 

 This, however, is not the case. It is very convex and finely reticular, covered with 

 minute lenses (see fig. 6). Bat it appears to be but loosely connected with the free 

 cheek, a very unusual character, and of course this would make it easily separable, 

 for there is no real connection with the upper eye-lobe in any Trilobite possessing a 

 facial suture. Mr. Hollier's little specimen figured above in the plate, fig. 3, shows 

 the cornea apparently connected with the upper lobe. The very perfect young head 

 (fig. 4) (Mr. Edgell's) has the same appearance. The cornea seems to be soldered to 

 the upper lobe, and divided from the supporting free cheek. But this is an appearance 

 only, as fig. 6 plainly shows. 



Locality — Woolhope Limestone, [Woolhope Valley, Herefordshire, ?] Malvern ; 

 Dudley, abundant. Wenlock or Ludlow rocks. Marloes Bay, Milford; Llandeilo. 

 I am not quite sure if this or the following species be the one found in numerous frag- 

 ments along the South Welsh Silurian border. 



Foreign. — Niagara Limestone of North America ; abundant. 



Homalonotus cylindricus, n. sp. PI. XI, fig. 12, and woodcuts, figs. 27, 28. 



H. 6-uncialis, convexus, minute granulosus, {capite triangulato ?) caudd longd pro- 

 ductd. Thorax convexissimus, insuper planatus. pleuris longe deflexis, axe angusto postice 

 contracto. Cauda longa trigona, axe longiconico 10-costato, et apice lave circumscripta; 

 mucrone lerminali elongato cylindrico distincto vix elevato ; costis lateralibus 7 convexis, 

 haud marginem verticalem angulatum attingentibus. 



