300 THE VOYAGE OF H.M.S. CHALLENGER. 



1857. KiRKBY, J. W. 



On some Permian Fossils from Durham, Plate VII. The Quarterly Journal 

 of the Geological Society of London. Volume the Thirteenth, 1857. London. 

 MDCCCLVII. pp. 213-216. 



For a fossil from the Magnesian limestone of Durham, -which Kirkhy considers to be the same 

 as Trilohites prohlematicus, Schlotheim, and Palxocrmujon ■prohlematica, Schlauroth, he 

 gives the name Prosoponiscvs jiroVlematicus, deriving the new generic name " from Trpocrwrrov 

 a face or mask, and oi-t'o-Kos, oniscus," as better expressing the affinities of the fossil. 

 " In aU," he says, " six specimens have been obtained ; two from Humbleton Quarry, 

 three from Field House, Ryhope, and one from TunstaU HLU." He does not say on what 

 he relies for the generic characters, but describes the fossil as follows : — referring first to a 

 specimen " showing the cephalic segment or carapace, with two body-segments attached 

 (PL VII. figs. 1, 2, 3)." 



" The carapace is about as long as four of the succeeding body-rings, somewhat less in depth, and 

 slightly compressed laterally ; it is carinated along the back and wedge-shaped in front ; tlie 

 eyes are large, round, and prominent, and are placed far forward ; from the lower part of 

 each eye runs an indented Une, at a short distance from the margin, up to the dorsal region, 

 where it curves forward. 



" The other five specimens consist of body-rings (2 to 6 in number) and the two great posterior 

 or caudal segments ; and are very similar to the figures given by Schlauroth. In one of the 

 Dui'ham specimens (fig. 7) there are six body-rings, and two posterior segments ; the others 

 (figs. 4, 5, 6) have likewise the two latter segments, but not so many of the former. The 

 body-segments are narrow, almost uniform in size, but varying a little in depth, the central 

 ones appearing to be the most produced ; they overlap each other and the penultimate 

 segment posteriorly ; they are slightly compressed, and have traces of a median dorsal 

 ridge ; those in front have their extremities turned a little forward, while the posterior ones 

 are bent in the contrary direction. The large penultimate segment is greatly developed 

 laterally ; it is strongly carinated dorsaUy ; its ventral margins are slightly convex, as is also 

 the posterior border, which has a deep notch not far from the dorsal ridge ; the ridge or 

 keel of this segment is very prominent except anteriorly, where at each side of the dorsal 

 ridge is a transverse swelling ; it is compressed also posteriorly. The next segment, which 

 is the hindermost known, is more compressed than the preceding one, and considerably 

 smaller. 



" None of the English specimens show the true external surface, nor have any traces of feet or 

 of antennae been found. 



" The specimen with the carapace (figs. 1-3) is one-eighth of an inch long. The largest of 

 those with the body-segments only (fig. 4) is nearly half an inch in length." 



Since Prosoponiscus is no more appropriate to an Amphipod than Palsmcrangon, it is obvious 

 that Sclilauroth's earlier name must take precedence. 



1857. Leydig, Franz. 



Lehrbuch der Histologie des Menschen und der Thiere. Frankfurt a/M. 1857. 



Leydig in 1878 gives references to this work, pages 341, 342, 362, 441, with regard to the 

 adipose body, the liver, and the circulation in Gammanis. 



