On Some Carboniferous Arthropods. 143 
not as yet illustrated. For the privilege of describing these interesting 
fossils I am much indebted to Mr W. F. P. M‘Lintock, who is at present the 
custodian of the collection, more especially to Sir Carlow Martin, the Director 
of the Royal Scottish Museum, for his consent to their being described by 
me, and also to Dr James Ritchie for access to specimens of recent rolling 
Myriapods and Crustacea. 
MYRIAPODA. 
Sub-Clas CHILOGNATHA. 
Tribe ONISCIFORMA. 
Paleospherotherium,! gen. nov. 
Description of Genus.—Rolling Myriapods with tergites similar to Sphero- 
thervum, but differing from it in having fourteen instead of thirteen tergites. 
Paleospherotherium walcotti,? spec. nov. [Pl. IV. Figs. 1, 2.} 
Preliminary Remarks.—The genus and species are based upon a single 
specimen preserved in the round within a clay-ironstone nodule. The dorsal 
and dorso-lateral view of only thirteen tergites is exposed, the head and the 
first tergite having evidently been displaced before the entombing of the 
remains. 
The thirteen tergites preserved are mostly in natural relation to each 
other, though they have been somewhat obliquely compressed and distorted. 
The anterior portion of the specimen, back to the eighth dorsite, is partially 
rolled and slightly bent towards the right, and some of the tergites are 
partially and irregularly telescoped into each other. 
Description of Species——The specimen measures, in a straight line, about 
14 mm., but considerably more along the curve of the back. The body is 
broadest and deepest about the eighth tergite whence it tapers gently forward 
and more rapidly and increasingly backwards. The test is plain and unevenly 
pitted with small punctures, but otherwise unornamented. 
lst Tergite.—This tergite has not been observed. Judging from the 
arching and the nature of the anterior margin of the second tergite the 
first must have been small, and must have rolled backwards beneath the 
second as in the modern onisciform chilognaths. 
2nd Tergite—The second or nuchal tergite, the foremost one preserved, 
1 The name is intended to show the near relationship of this Paleozoic animal to the 
recent Spherothervwm. 
? Named in honour of Dr Chas. D. Walcott, of the Smithsonian Institute, Washington, 
formerly Director of the U.S. Geological Survey, who has brought to light so many early 
Paleozoic Arthropods. 
