66 Proceedings of the Royal Irish Academy. 



present genus and in Arthropleura. From Kliver's figures there can be little 

 doubt that Arthropleura was, like Oxyuropoda, onisciform in build. The 

 general facies of Oxyuropoda is highly suggestive of the Oniscoidea ; a 

 superficial likeness to Ligia is apparent at a glance, and some true relation- 

 ship is by no means improbable. But if our interpretation of the first 

 thoracic segment and its appendages be justified, Oxyuropoda shows distinct 

 affinity to the Chelifera, a tribe of the Isopoda, so aberrant as to be placed by 

 many modern students in a distinct order, the Tanaidacea, and hitherto 

 imknown in the geological record. The Oniscoidea have not been traced 

 further back in time than the Miocene. It will be of some zoological 

 importance should further specimens of Oxyuropoda, in which the ventral 

 surface and appendages may perchance be well preserved, show that the 

 genus forms a Palseozoic link between the two divergent tribes of the 

 Chelifera and Oniscoidea, both apparently modern, and each in its own way 

 highly specialized. Further, the close association of the first thoracic 

 segment with the head, the dorsal position of the eyes, and the somewhat 

 trilobitic aspect of the body, are features in which our fossil resembles the 

 Serolidfe — a family of the tribe Flabellifera, whose members have the 

 uropods laterally situated, as they are in Oxyuropoda. This Devonian 

 genus, therefore, as might be expected, suggests several interesting lines 

 of connexion between various tribes of recent Isopoda. 



The question of possible affinity with the Oniscoidea raises the question 

 whether, like most members of that tribe, Oxyuropoda lived on land. Its 

 large size, and the presence of the Archanodon in the same beds, suggest 

 rather the probability that it was a denizen of the old Devonian lakes ; though 

 the abundance of fern fronds in the Kiltorcan rocks forbids us to deny the 

 possibility that our Isopod may, with them, have been derived from the 

 neighbouring land-surface over which it had crawled in life. 



Eeferences. 



1870. W. H. Baily. — On Fossils obtained at Kiltorkan Quarry, County 

 Kilkenny, Brit. Assoc. Eeport, xxxix., 1869, pp. 73-5. 



1861. J. Beete-Jukes and W. H. Baily. — Explanations to accompany 

 Sheets 147 and 157 of the Geological Survey of Ireland. Dublin 

 and London, 1861. 



1885. M. Kliver. — Ueber Arthropleura armata, Jord. Palseontographica, 

 xxxi., 1885, pp. 11-18, taf. 3 and 4. 



