OF THE SPECIES. 103 



SECTION II. 



TrUohites possessing the eapacifi/ of rollhif/ themselves up, the bochj axis not shortened 

 posteriori!/, the shell finely lineated, the caudal shield not having radiated lateral farrows. — 



AsAPHin.E. 



I have already made some necessary remarks respecting the structure of the shells of 

 this group ; an additional common characteristic, however, seems also to exist in the 

 glabella, which is always simple and destitute of lobes, indistinct traces only of lateral 

 lobes being occasionally recognized at its posteiior contracted part. The caudal axis 

 likewise has frequently no joints, but generally has thera indistinctly marked, whilst the 

 ribs on the sides of the shield are always entirely wanting, and are at the utmost only 

 indicated by fine ridges or lines. With regard, however, to the width of the body rings 

 I must remark that the central rings become rather broader than the anterior and posterior 

 ones, and the axis has, therefore, only an equal width at the anterior and posterior part. 



A. 



Tlie body axis consisting of ten equal rings. 

 Genus 17. — Ill^nus, (Ill^nus and Bumastes.) 



The cephalic shield may be best compared to the fourth part of a sphere, and is, 

 therefore, bounded by curves on the posterior and anterior margins, and strongly arched 

 between ; at the posterior margin we recognize the glabella as a slight convexity on the 

 surface ; the anterior margin, on the other hand, is acutely angular, rather produced, 

 and depressed. 



The facial suture projects obliquely over the flattened margin, rises with a gentle 

 curvature upwards to the eye, forms the covering plate over the latter, and thence turns 

 again with a gentle curvature towards the posterior margin, which it intersects not far 

 from tlie axis. Both sutures are connected on the flattened anterior margin by a transverse 

 suture. 



The eyes are semilunate, depressed, and smooth. 



The body consists of nine or ten short but broad rings, which are not furnished with an 

 oblique transverse furrow on the lateral lobes. 



The large, almost semicircular, caudal shield is highly arched, and furnished with an 

 indication of a short axis, as in Brontes. 



The surface of the shell has fine, concentric, irregular lines or ridges, between which, as 

 also on the parts which are not striated, there are impressed punctures. 



Division A. — Axis of the body not broader than the lateral lobes, and distinctly sepa- 

 rated from them. — Illj^inus, auctorum. 



The species occur in the lower strata of the grauwacke formation. 



1. ///. crassicauda : Oculis margiui postico scuti ceplialici approximatis. Long. 1-3". Tab. V, 

 Fig. 2. 



Entom. cr. Wahlenb. N. A. Ups. viii, 27. 2, Tab. II, Figs. 5, G. Dxhyi. Pal^ad. 51. 12, 

 Tab. V. Fig. 2, «,/. Bronn, lefh. i, ll',, C. 3, Tab. IX. Fig. 9, a, b. Boeck, 



