668 MR. B. K. PEACH ON THE EA.UNA OP THE [Nov. 1 894, 



margin to the posterior margin, is rounded in front, broadest at the 

 base of the eye-lobes, and narrowest to just behind the second 

 furrow. It then increases in breadth backward. It is divided 

 into five lobes by furrows which are not so much bent backward in 

 the middle as in 0. Lapworihi. A small tubercle occurs on the 

 occipital ring. The eye-lobes are reniform, and set out at more 

 obtuse angles than in any of those already described ; they extend 

 back only so far as to be opposite to the second glabellar farrow. 

 The area in the angle made by the glabella with the eye-lobes is tumid. 

 The test is ornamented with the characteristic reticulate pattern. 



Measurements : — 



Length of head-shield 3 mm. 



Breadth of do 7-5 „ 



Length of genal spine 2 - 5 „ 



Olenelloides, subgen. nov. 



The collection of fossils from Meall a' Ghubhais contains numerous 

 head-shields, and one specimen and its counterpart with head- 

 shield and eight body-segments attached, of a peculiar, small, narrow 

 trilobite armed with long spines at regular intervals. It is evident 

 that it is nearly allied to Olenellus, in which genus I should prefer 

 to allow it to remain ; but though all the specimens may belong to 

 only one species, yet the individuality of that species is so strongly 

 marked that perhaps it would be better to place it in a separate 

 sub-genus taking rank with Holmia and Mesonacis under Olenellus. 

 The name that I have proposed for it is intended to show its strong 

 likeness to some larval stages of other Olenellids. 



Description. Small, elongated, and narrow in general outline, and 

 set with long spines at regular intervals. 



Head-shield roughly hexagonal, produced into long and strong 

 spines at all the angles, and strengthened on all sides except the 

 posterior one by a strong, rounded, raised margin, which is widest at 

 the angles. Its greatest width is across from base to base of the 

 mid-pair of marginal spines. The glabella, which occupies about 

 half the area of the head-shield, is well embossed, almost cylindrical, 

 divided into five distinct lobes, and extends nearly the whole length 

 of the shield. It is rounded in front, slightly constricted near the 

 second furrow, and widest at the occipital ring, which bears a small 

 blunt tubercle in the mid-line. The eye-lobes are reniform, pro- 

 ceeding out from the frontal lobe just in front of the first furrow, 

 and with their distal ends well set out from the glabella. The visual 

 slits occupy nearly the whole length of the outward or convex 

 edges of the eye-lobes. No free cheeks nor facial suture. 



Number of body-segments unknown. The characters of the eight 

 preserved show that the body was long and narrow, and that the 

 segments are well trilobed, with highly embossed axes, which are 

 wide compared with the pleura. The latter are marked off from 

 the axal parts by a shallow furrow, have fulcral thickening in front, 

 wide fulcral grooves, and end in short spines at the postero-lateral 

 angles, except in the third and sixth segments, where the spines are 



