CRUSTACEA AND ARACHNIDA OF THE CARBONIFEROUS ROCKS. 527 
Cyclus testudo, nov. spec., Pl. XXVIII. figs. 9-9d. 
Body discoid or dome-shaped, varying from 3°5 to 10 mm. in length by 
2°5 mm. in breadth, and divided into a larger anterior area or carapace, and a 
smaller posterior area or abdomen. The carapace, which occupies the larger part 
of the body, is rounded in front, and produced backwards into two horns like 
Limulus, which, however, lie close in to the body, and hold the abdomen wedged 
as it were between them. The carapace, at least in the crushed specimens at 
command, is itself divided into two areas, a broad horseshoe-shaped area occupy- 
ing the whole of the anterior and lateral margins, doubtless due to the infolding 
of the margin of the carapace as in Limu/us, and an interior or dome-shaped 
area, which does not seem to have been subdivided into lobes. The whole of 
the carapace, as well as the rest of the dorsal portions of the test where not 
infested by calculi, are minutely pitted or corrugated. In many cases the 
central area has broken away, so as to expose the interior of the sternal portion 
of the animal to view. In such specimens six triangular plates on each side, 
divided from each other by deep sulci, are seen to converge upon an oval sternum ; 
these are smaller in front, and become larger and longer backwards, and the 
point towards which they converge is situated within the anterior half of the 
carapace. They do not complete the whole round, for there is a larger median 
plate behind, which, however, appears to belong to the abdomen. The former 
plates are the cox of limbs, which are seen to pass from the outer sides, beneath 
the broad horse-shoe band, which is still left on the fossils, and to appear out- 
side it as jointed cylindrical limbs, the tips of which have not been observed. 
The abdomen is very small compared with the carapace, and appears to have 
been buckler-shaped, and to have terminated in a short pointed telson. The 
nature of its articulation to the carapace, and the character of its appendages 
cannot be made out from the specimens at command. 
Collector.—H. MAcconocuie. 
Locality.—Langholm. 
Horzon.—Calciferous Sandstone Series. 
VOL. XXX. PART II. 4N 
