BY R. ETH BRIDGE, .TUNR., AND JOHN MITCHELL. 047 



access to the original description) became the generic type. We 

 are, however, able to refer to Hawle ct Corda's work,* published 

 only two years after the appearance of Emmrich's description. 

 These authors describe the above trilobite as it is now generally 

 accepted, and very carefully traced the course of that most im- 

 portant feature, the facial suture, in the following words: — "The 

 frontal suture arises on the exterior margin of the cephalon below 



the spine (genal) passes obliquely upwards and inwards 



to the posterior angle of the eye, round the eye operculum [palpe- 

 bral lobe] and curves inwards from the anterior angle of the eye 

 and the two (facial sutures) unite on the point of the forehead 

 above the inflected somewhat serrated head margin." They also 

 note eleven segments in the thorax, and the non-segmented con- 

 dition of the pygidial axis; but no remarks whatever are made 

 about the existence of glabella furrows. 



The type, E^icrimirtis jmncfatus (as Cyhele. ininctata)^ was 

 described from Wenlock Limestone specimens by Mr. J. W^ 

 Fletcher;! and his remarks are important in that his description 

 of the glabella clearly indicates the difference existing between 

 that portion in Encrhiuriis and Cromus respectively. He said 

 that "two or three large tubercles arranged on each side of the 

 lower half of the glabella, occupying the situation of the lateral 

 lobes, the furrows between which are not visMe" (the italics are 

 ours). To follow the whole literature bearing on Encrinurus 

 would be tedious, and is unnecessary, but two references in par- 

 ticular may be quoted. The first comprises the beautifully 

 engraved figures of three species {E. sexcostatus, Salter, E. vario- 

 laris, Brongniart, and E. pwnctatus, Briinnich).! In the three 

 views of the glabella of the first of these, lateral furrows are 

 clearly represented and described, but in the other two these 

 furrows are not. E. sexcostatus \^ therefore, from our point of 

 view, a Cromus, and no doubt would have been so designated by 



•Hawle & Corda, Prod. Mon. boheni. Trilobiten, 1847, p.90. 

 tFletcher, Quart. Journ. Geol. Soc, 1850, vi., p.403, PI. xxxii., figs.1-5. 



T Salter, Mem. Geol. Survey U. Kingdom. Figs, and Descriptions Brit- 

 Org. Remains, 1853, Dec. vii., No. 4, PI. iv. 



