Carpenter and Swain — A neiv Devonian tsopod from Kiltorcan. ^^ 



The thoracic segments of this animal evidently resemble rather closely 

 those of the Carboniferous isopod Arthropleura, as described and figured by 

 Kliver (1885). We believe that he has in some cases regarded as segmental 

 divisions what are really nothing but transverse ridges on the terga, 

 comparable to those in the present genus. For example, the terga of 

 Arthropleura arrtiata, Jordan, which he figures (taf. 3), and states in his 

 description to be " im Ganzen etwa sieben," probably represent three or 

 four segments only. 



In the hindmost thoracic segment (fig. 1, 7) the arched ridges reach the 

 lateral margin well in front of the hind corner of the pleura. A crescentic 

 area (fig. 3, i.) at the posterior edge of this segment probably represents the 

 first abdominal tergum which is, perhaps, fused with it. 



A number of irregular wrinkles on the dorsal surface of the terga and 

 pleura suggests that the cuticle of the animal was somewhat flexible- 

 Beneath the third thoracic segment can be clearly traced the outline of two 

 terminal segments of one of the short walking-limbs with a straight terminal 

 claw. This outline is shown (fig. 1), its base connected by a dotted line 

 with its apparent position of attachment. 



Ahdomen. — There are four abdominal segments, the pleura of which are 

 produced into conspicuous, backwardly-directed processes. These appear to 

 be the second, third, fourth, and fifth (fig. 3, ii., iii., iv., v.) ; each has a pair 

 of tubercles on the tergum — the fifth tergum also a central tubercle — and 

 indistinct ridges at the boundaries of terga and pleura. The first abdominal 

 tergum is probably represented by the crescentic sclerite (fig. 3, i.) closely 

 associated with the last thoracic segment. 



The abdomen terminates in a small rounded segment with its hinder edge 

 slightly emarginate and crenulated. This bears laterally the curious 

 unjointed, acuminate uropods already mentioned. Each of these appendages 

 has a thick rounded base, and tapers gradually to a needle-like point ; a 

 distinct ridge can be traced along the dorsal surface, and an elongate flat 

 lamina along the outer edge ; possibly the latter is the exopodite, but there 

 is no clear evidence that the appendage is biramous. 



There are several points of interest arising from the discovery of this 

 fossil. Hitherto only a few Palasozoic genera of Isopods have been known. 

 Prsearcturus (Woodward), and Amphipeltis (Salter), from the Devonian of 

 Herefordshire and Nova Scotia respectively ; and Arthropleura (Jordan), from 

 the Carboniferous of Germany and England (see Zittel, 1885 and 1900). 

 These genera are so imperfectly known that the relationship between them and 

 Oxyuropoda must remain for the present problematical ; but attention has 

 already been called to the likeness between the thoracic segments in the 



