116 



Contributions to Palaeontology. 



CRUSTACEA. 



GENUS DIKEL CEPH ALUS (Owen). 



" Cephalic shield semicircular and rather flat. Glabella 

 " moderarely convex, equally wide throughout, rounded 

 " in front, divided by two furrows into three distinct 

 "lobes: these well marked furrows extend quite across 

 "the glabella, and form a curve or slightly obtuse angle 

 " in the median line directed backwards. The anterior 

 "lobe is partially divided by a third obscure furrow, 

 "which becomes obsolete in the median line. 



"Facial sutures distinct, originating in the anterior 

 " [posterior] border of the cephalic shield : they run at 

 "first parallel with the same; then converging in a 

 " sigmoid flexure around the eye-plate, diverge again 

 "incurved lines, until, reaching the anterior border, 

 "they circumscribe an area of greater or less extent in 

 " front of the glabella. 



" The cheek-plates produced at their anterior [posterior] 

 " corners into spines of moderate length. 



" Pygidium rather deeper and about the same width as the 

 " cephalic shield, with from four to six segments ; the 

 " last and largest segment sometimes obscurely subdi- 

 vided by a faint furrow. Lateral and interlateral seg- 

 " ments blended into a marginal flap or border of greater 

 "or less extent: usually, if not always, provided with 

 " caudal spines." 



In the form and expression of the glabella, there is 

 considerable resemblance to Paradoxides, except that it 

 is not expanded in front. The direction of the facial su- 

 ture, however, is conspicuously different. The extended 

 frontal limb in the typical species does not appear to be a 

 generic feature ; for in the I). pepinensis of Owen it is 

 narrow and convex. The thoracic articulations are marked 

 by a simple groove running out at the lower margin of the 



