BY K. ETIIEIUDGE, JUXR., AND JOHN MITCHELL. 711 



In C. Verneitiii, however, the pleural are flattened from above 

 quite similar to our figures of C. Vogdesi. 



The same features separate it from C. vesiculosa. 



Mr. Ratte referred to the disputed point of the existence of 

 an articulation between the pleura? and the axial segments, said 

 to exist in some trilobites by Emmrich, and disputed by Bur- 

 meister, the latter being upheld by Barrande. Mr. Ratte basing 

 his opinions upon certain features one of our figured specimens 

 exhibits, was inclined to support Emmrich's view. He says : — 

 " One cannot help being struck in examining the specimen in 

 question at the great resemblance to an articulation of the 

 junction of the axis with the pleurae. It seems as if the test (or 

 its different joints) had been covered by a thin epiderm as 

 admitted by Burmeister,* and that this epiderm is wrinkled at 

 the articulation as shown in fig. 5, and especially in the enlarged 

 sketch fig. 8."t 



Whilst admitting the ^•ery joint-lilvc appearance, somewhat 

 exaggerated in Ratte's figure, we do not see any direct evidence 

 of the jointing; but, on the contrary, there is one strong feature 

 we have observed which disposes of the question in favour of the 

 negative, and, that is, in all the many thoracic segments which 

 have come under our notice, we have never seen a specimen 

 divided at this point. 



This joint-like appearance at the ends of the thoracic axial 

 segments is also seen in the type of Selenopeltis [S. Buchi', 

 Barr., sp.) 



Ratte figured the principal tubercles of the pleurfe surrounded 

 by a complete circlet of granules in every respect resembling the 

 primary tubercle and its miliary ring on the interambulacral 

 plates of an ordinary Echinid, such as the genus Cidaris. His 

 figures correctly represent the specimen used by him, but on no 

 other specimen can we find this feature nearly so distinct. 



* Barrande, loc. cit. p. 231. 

 t Proc. Liun. Soc. X.S. Wales, I. (2i, p. 1068, t. 15. 



