2 



BRITISH FOSSILS. 



we liave hitherto considered it identical, although there are 12 

 body rings to the latter, and only 11 in Encrinurus. But the 

 delineations of the facial suture given by Drs. Volborth and 

 Kutorga in the Transactions of the Royal Mineralogical Society of 

 St. Petersburgh, 1848, show that in this important particular, as 

 well as in the number of bod}^ rings, the two genera differ ; and 

 when to this is added that the hinder segments of the thorax are 

 not in Encrinurus produced into long spines but are all equal, we 

 have a combination of characters sufficient to justify the separation. 

 But there are species of Gyhele whose habit is so like that of 

 Encrinurus, that should a species hereafter be found with the facial 

 suture of one of these groups, and the number of body rings 

 distinctive of the other, we should recommend their reunion as 

 sections of one natural genus. 



Description. — Length about an inch and a half, breadth an inch. 

 Some specimens must have been larger. General form broad-ovate ; 

 the head and tail convex, the body rather flat. Head about equal 

 in length to the tail, but shorter than the thorax ; its shape 

 triangular, the lateral angles produced, the front rounded, gibbous, 

 and overhanging. The glabella occupies full one third of the width 

 of the head in fronts where it is much inflated and more than 

 hemispherical ; it overhangs the margin, which, as is usual in the 

 genus, is not distinctly separated from it in front, but within the 

 margin and above it on the glabella, there is a strong furrow which 

 runs quite across the glabella, separating from it a thick prominent 

 ridge (fig. 3, a) so completely that it appears not to form a part of 

 the glabella, but to belong to the thickened front margin.* The 

 entire glabella is pyriform, constricted behind to half its width, and 

 separated by a strong sulcus from the neck segment, which is broad 

 and prominent. It is indented half-way up by three short furrows 

 on each side. The cheeks, though convex, are much less so than the 

 glabella, and they bear the eye in the middle of the cheek. In our 

 specimen the eyes are broken off, but in all probability they were 

 elongated, and directed forwards and outwards, as we have indi- 

 cated by the dotted lines in our fig. 2. The outer margin of the 

 cheek is thick, and separated by a furrow, and the posterior angles 

 are produced into spines ; the posterier edge also has the strong 

 neck farrow continued along it. The glabella is covered with 

 tubercles of unequal size, mixed with granules, but the specimen 



* This singular furrow is probably the place of the facial suture, which in this genus 

 crosses the front of the glabella. This suture is not visible in our specimens*, but its course 

 in front is well seen in E. variolar is, figs. 13 and 14, a a. 



