148 MP. E. P. COWPEK PEED ON THE EATJNA OE THE [May 1909, 



Acidaspis(?) sp. (PI. VI, fig. 8.) 



One imperfect pygidium, the generic reference of which is some- 

 what uncertain, has been found in the calcareous ashy grit (212), 

 south of Gortbunacullin. Only the spinose margin and a small 

 piece of the edge of the lateral lobes are preserved. 



In shape the pj-gidium is broadly parabolic or semielliptical, about 

 twice as wide as long; the surface was apparently rather strongly 

 convex, and the lateral lobes, which are devoid at the edge of all 

 traces of pleurae, descend steeply to the narrow flattened border, 

 which is furnished with five pairs of somewhat flattened spines, 

 horizontally extended and subparallel, being all directed nearly 

 straight back with scarcely any perceptible divergence. They are 

 of subequal size and stoutness, and situated at equal distances 

 apart ; their length cannot be ascertained, as their ends are 

 broken off, but the portions remaining are about half the length of 

 the pygidium. They taper very slowly, and all apparently at the 

 same rate, and it is probable that they were all of subequal length. 

 The surface of the lateral lobes and of the spines is covered with 

 minute tubercles. 



Dimensions. — Length (without spines) = 2-75 millimetres ; 

 width = 6 mm. 



Remarks. — It is possible that this fragmentary pygidium should 

 be placed in the genus Acidaspis, but the marginal portion of a 

 pygidium like Apatocephalus serratus (Ececk), with the spines more 

 regularly spaced, would have a very similar appearance to our fossil. 



Apatocephaltts (?) sp. (PI. VI, fig. 9.) 



One isolated free cheek measuring about 10 millimetres in length 

 and 5 mm. in width, occurring among the specimens from (322), the 

 gritty ash a third of a mile south-south-west of Shangort, shows 

 features which demand a special notice of it. 



The cheek is elongated and narrow, about twice as long as wide, 

 and the genal angle is furnished with a spine. The surface of the 

 cheek is convex, and rises rather steeply from the marginal furrow ; 

 it is covered with rather coarse, low, closely set tubercles and 

 bears a large, gently curved eye, which is about half the length 

 of the cheek, is placed far back but does not touch the neck-furrow 

 behind, and is supported by a steep, low, smooth base surrounded by 

 a wide shallow furrow : the lenses and surface of the eye itself are 

 unfortunately not preserved. The lateral margin of the cheek has 

 but a slightly arched outline, and is provided with a moderately-wide 

 smooth border, inclined less steeply than the surface of the cheek, 

 from which it is marked off by a shallow furrow, and provided with 

 a rounded rim. A conspicuous but low rounded swelling forms an 

 oval boss at the angle of junction of the marginal and neck-furrows, 

 and is partly separated from the convex surface of the cheek. The 

 neck-segment is smooth and marked off by a strong neck-furrow 

 which is directed nearly at right angles to the marginal furrow. The 

 genal angle is provided with a long gently-tapering spine which is in 



