118 



[Senate 



sterior margin nearly straight across the centre, and a little concave at the sides; 

 anterior and lateral margins somewhat thickened. The facial suture ( to judge 

 from the separated parts) is very simple, extending in a slightly curving line 

 from the front of the shield backwards, and coming to the posterior margin 

 within the limb. The glabella is prominent and well defined, ovate in form and 

 gradually narrowing towards the front : the occipital furrow extends directly 

 across the glabella ; the first pair of furrows above this are oblique and only 

 slightly connected across the middle of the glabella, while anterior to these are 

 two slight indentations. Hypostoma subcircular, with the posterior end a little 

 wider. Eyes unknown. 



Thorax composed of eleven articulations ; the axis broad and prominent, wider 

 than the lateral lobes. Lateral lobes nearly flat, narrow : the first five or six 

 ribs short and narrow, inclining gently backwards; the posterior ones becoming 

 more abruptly bent and prolonged at the extremities, while the last pair are 

 wider and stronger, bent almost rectangularly, and produced in spiniform 

 extensions much beyond the others. 



Ptgidium distinct, semioval, the axis marked by several annulations, the lower 

 part plain. Lateral lobes plain or marked by ridges, and extending beyond the 

 axis in a continuous flattened expansion. 



BATHYNOTUS HOLOPYGA*. 



There are but three distinct rings in the 

 axis of the pygidium, though there is a 

 fourth indistinct depression, which may or 

 may not indicate a fourth ring. 



BATHYNOTTTS HOLOPYGA. 



The single species described in the last Report is illustrated in the accompanying 

 figure. The specimen is a mould or impression from which most of the crust has 

 been removed, and we have the relief from a cast made in this mould. The cheeks are 

 separated and turned on one side; but in the drawing, they are placed in symme- 

 trical relation with the other parts of the animal. The rings of the axis are marked 



♦ OUniis (Peltura) holopyga : Twelfth Annual Report of the Regents of the University, 

 on the State Cabinet of Natural History, p. 61. 



