[ 336 ] 

 PART II. 



DESCRIPTION OF THE FOSSILS^. 



TRILOBITES. 



1. Calymene macrophthalma, Brong., Hist. Nat. Crust. Foss. PI. I. f. 5. Pander, Beitrage z. Geog. des 



Russ. Reiches, PI. IV. B. f. 8. Murch., Sil. Syst., PI. XIV. f. 2. 



We have found this species in the roofing-slates of Wissenbach. It is known to be one of the most 

 abundant in the Eifel, but, on the contrary, it is very rare in the properly so-called Silurian system. 

 Mr. Murchison remarks, that in England it is much less abundant than the Calymene Blumenhachii and 

 the Asaphus caudatus. Pander found only a single specimen in Russia. It also occurs at Prague and 

 in North America, but it has not yet been mentioned as Swedish \. 



2. Calymene concinna ? Dalman, Ueber die Paalden oder die sogenannten Trilobiten, PL I. f. 5. 



The slates of Herborn are often filled with impressions of the post-abdomen of a Trilohite which ap- 

 pears to be related to Calymene concinna ; but the difference in the age of the beds in which our fossil 

 occurs and the incompleteness of the specimens do not permit us to insist upon their identity with Dal- 

 man 's species. 



3. Calymene granulata. Munst. Beitr. Petref., iii. Heft, PI. V. f. 3, id. Phil. Pal. Fos., PI. LVI. f. 248. 



Sedg. and Murch., Geol. Trans., vol. v. PI. LIV. f. 24. 



We found in the limestone of Oberscheld the post-abdomen of a Calymene, which appeared to us very 

 like that which Prof. Sedgwick and Mr. Murchison have figured in their Memoir on Devonshire. 



4. Asaphus subtyrannus, nob. 



Tail short and broad ; articulations of the lateral lobes much inclined toward the end of the tail, and 

 joined to the middle lobe at a very decided angle. These articulations are united by a membrane 

 which goes all round the post-abdomen, and they are about half as wide again as those of the 

 middle lobe. Both are granulated, but the grooves which separate them are quite smooth. 

 Width of the middle lobe, 18 millim. ; of the lateral lobes, 24 millim.J. 



This Trilohite should be placed near to A. tyrannus var. ornata (Murch., Sil. Syst., PI. XXIV.), from 

 which it is distinguished by its less slender form and by the disposition of its granulations, which in A. 

 tyrannus are seen both on the ridges and on the grooves which separate them. But since, according 

 to Mr. Murchison, individuals of ^. tyrannus are found which do not present any traces of granulations, 

 it is possible that the examination of a greater number of specimens from Wissenbach might compel us 

 to unite our species to that of Mr. Murchison, which has only yet been found in the lower beds of the 



* We refer to the general Table at the end of this memoir for all the species already described, upon 

 which we have no observations to offer. 



t We preserve for Calymene macrophthalma the name at first assigned to it by M. Brongniart, and 

 which is the most generally known ; but this fossil has received several other denominations which ap- 

 pear to authorise the establishment of the genus Phacops, in which M. Questedt has united C. macro- 

 phthalma and C. sclerops, 



\ A millimetre is equal to 0'03937 of an English inch, and a centimetre equals 0*393708 of an En- 

 glish inch. The English inch equals 2*539954 centimetres : thus to bring any number of millimetres into 

 English inches and fractions of inches, it is only necessary to multiply that number by the decimal 0"03937. 



