290 MR. E. S. COBBOLD ON TRILOBITES [Aug. I9H, 



Axial lobe. — Strongly convex in cross-section, and considerably 

 curved longitudinally ; slightly narrowing posteriorly ; greatest 

 width equal to about a third of that of the pygidium ; divided by 

 six deep and wide furrows into an anterior, articulating facet, 

 and six other segments of subequal breadth : of these, the five 

 anterior are provided with short, strong, and straight spines pro- 

 jecting upwards and backwards ; the sixth or terminal segment 

 has a well-marked node in place of a spine, and ends in a steep 

 slope down to the flattened border of the shield. 



Axial groove.- — Very slightly marked along the sides of the 

 axis. 



Lateral lobes. — Sub-triangular; evenly convex outwards ; not 

 connected together behind the axis ; each lobe consists of six ribs ; 

 the anterior rib is narrow and rounded ; the next three are much 

 wider and have their surfaces flattened transversely to their length, 

 and indistinctly marked with a wide furrow ; the two remaining 

 ribs are small, and only just discernible. 



Border. — Horizontal, and continuous round the sides and end 

 of the pygidium ; the width, exclusive of the spines, is about 

 a tenth of the length of the shield; the margin is armed with 

 six spines of flattened, oval section on each side. So far as can be 

 seen from the specimens, the length of these spines is sensibly the 

 same throughout, except, perhaps, in the case of the hindermost 

 pair, which have their bases slightly enlarged. 



Test. — The outer surface of the most perfect specimen [181] 

 (PI. XXV, fig. 8 a) is a little corroded, and exhibits a finely granular 

 surface. Other fragments [183, 184] have their surfaces thickly 

 covered with raised granules, all the way from the axis to the spines. 

 This granulation is somewhat more minute than that of the head- 

 shield, but may be regarded as a further modification of that of 

 the fixed cheeks. 



The pygidia described are nearly allied to those of Borypyge 

 oriens Gronwall, 1 but differ in certain respects. In his species the 

 two posterior marginal spines are much longer than the others, and 

 have enlarged bases to correspond ; they also diverge one from the 

 other: while those of the Comley pygidia are little, if at all, longer 

 than the rest, and project directly backwards in the line of the 

 axial furrows. To judge by the figures and restoration given by 

 Dr. Gronwall, the Bornholm species is somewhat narrower than the 

 Shropshire form, and the five anterior pairs of spines are, propor- 

 tionately, somewhat shorter. 



The test of Dorypyge oriens is described as being smooth, while 

 that of D. lalcei is decidedly granular, and the glabella is quite 

 rugose (see PL XXV, fig. 5). 



I have attempted a restoration in outline of this species (see 

 the accompanying text-figure, p. 291). The number of thoracic 

 segments (eight) is inserted from the analogy of other species. The 



1 K. A. Gronwall, Danmarks Geol. Undersog. ser. 2, No. 13 (1902) pp. 135 

 & 216, pi. iii, figs. 13-15. 



