8 



BRITISH FOSSILS. 



no trace of the curved spine characteristic of this sub-genus. Our 

 figured specimens had not the free cheeks in any case. Mr. Edgell's 

 specimens show them well. 



Body short; of seven rings only,* with a broad axis, showing in 

 the five front rings the central tubercle. The pleurae are short, 

 strongly grooved ; the two front ones without recurved spines, the 

 rest spinous ; the spines bent strongly back and about as long as 

 the pleura?. 



The tail is nearly a semicircle, and furnished with a strong conical 

 three-ribbed axis, wliich reaches the end. The sides two-ribbed, 

 with three spines on each side, the forward one longest, the other 

 two short, and leaving a rather broad smooth space at the extremity 

 of the tail beneath the axis. 



Locality and Geological Position. — Only known in the Black 

 Shales of Malvern, Fowlet's Farm, and Whiteleaved Oak Farm, &c., 

 and very abundant there, with other species of the genus next 

 described. 



OLENUS BISULCATUS. 



Plate YIII. Fig. 6. 



Diagnosis. 0. (Sph.) modicus, capite ti-ansverso^ glabella bisulcata, 

 genis latissimis. Thorax pleuris latis, profunde sulcatis, spinis validis 

 rectis. 



Synonym. 0. bisulcatus, Phill., Mem. Geol. Siu'v., vol. ii. pt. I, p. 55, 

 fig. 1. 



The head of this species is remarkably wide, and thus difi'ers at a 

 glance from 0. humilis, with which it occurs. The body rings 

 have lately been detected in the cabinet of my friend, Mr. Edgell, 

 and I am thus enabled to improve the description. The species is 

 stouter in all its parts than is usual in the sub -genus. 



The species is a small one, not more than eight lines in length, 

 and the width from tip to tip of the stout thorax spines seven Jines. 

 The head is very transverse, three times as wide as long, even ex- 

 cluding the free cheeks, which we do not perfectly know, but believe 

 to have extended somewhat further out, and to have been armed with 

 a stout curved spine starting one third or thereabouts above the genal 

 angle. The front is straight, or only slightly emarginate, and the 



* The species is abnormal for the genus, abnormal even for the sub-group to which it 

 belongs. It contradicts most of the technical characters of Olenus, and yet evidently 

 belongs to it. 



