OF THE SPECIES. 87 



B. — Species with thick, si/mmetrical spines on the whole surface of the back. 

 HoMALONOTus, Murcli. 



4. H. armatus : Tuberculo capitis octies spinoso, lateribus scuti ceplialici bispinosis; annulis trunci 

 bispinosis, rliachi caudse mutica. Long. corp. 3-6". 



Be/. — H. Greeiiii, Goldf. in Bronn n. Jahbr. 1843. 560. 5. 



Found in the grauwacke strata of the Eifel at Daun. The collection already alluded 

 to contains some fragments of this species, from which I have constituted it, and which I 

 shall now describe more particularly. It is comparatively broader than the other species, the 

 cephalic shield is hyperbohc, slightly reflexed at the circumference ; the glabella is furnished 

 with eight spines, namely, six larger ones in two rows, three on each side, and two smaller 

 ones close to each other, in the centre before the two posterior ones. The cheek-shield has 

 a large high spine at the sides, and rather behind the eyes ; besides this there is one spine 

 at each side, on the elevated part of the posterior margin, and one on its centre. The body 

 rings are each armed with two spines, one at each side, immediately before the front, 

 where they become transformed into the lateral lobes. 



Caudal shield short and small, the axis six-jointed, unarmed ; each of the sides furnished 

 with three ribs, of which the first bears a spine at each side ; the end of the sliield is oblong 

 pointed, in the form of a spine. 



5. H. HerscJielii : Annulis trunci quadrispinosis, lobis lateraliljus unispinosis ; rhachi caudse in basi 

 4 spinosa, lateribus miiticis. 



i?^/._MuRCHis. Sit. S?/sf. ii, 652, Plate VII, to Fig. 2. Milne Edw. Cri/st. iii, 315. 



Found in the upper Silurian strata of the Cedar Mountains, Cape of Good Hope, asso- 

 ciated with Cat. Bliiment)acliii and C. TristaniQ:). 



According to Murchison's figure, the caudal axis of this species consists of fourteen 

 joints, the two first bearing a spine at each side ; the sides seem to possess a number of ribs 

 equal to the number of joints, but no spines. Of the body rings we find seven ; they appear 

 to be furnished with four spines, two on each side, approximating to the lateral lobes ; and 

 besides these there is probably another one on the lateral lobes themselves. 



The cephalic shield is wanting. 



B. 



Tritot)ites having the power of rolling themselves up, whose facial suture terminates in the 

 external lateral margin of the cephalic shield. 



This section of Trilobites, originally established by Quenstedt, and confirmed by 

 Emmerich, includes only the genus Phacops, and appears not to require the generic sub- 

 divisions proposed by Milne Edwards and Goldfuss. 



