TRILOBITES OF THE LOWER SILURIAN ROCKS. 



661 



It would appear from the observations of Bigsby, and also from those of Dr. Green, that 

 the genus Trinucleus is very abundant in North America. I have not yet had an opportunity 

 of comparing good specimens, though it is probable that one of the specimens found by 

 Dr. Bigsby, near Montmorenci, and in the collection of Mr. C. Stokes, is our Trinucleus 

 fimbriatus, f. 2., called T. Bigsbii f p. 397. (See Geol. Trans, vol. i. p. 196.) 

 Calymene ? f punctata, /, 8 a, b. (Dalm. PI. 2. f. 2 a, b.) Entomostracites punctatus, Wahl., 

 (Brongn., PI. 3. f. 4.) 



The caudal portion of this trilobite, identical with the figures of Wahlenberg, Brongniart 

 and Dalman, is abundant in the Caradoc Sandstone. As neither the body nor head of the 

 animal have yet been found, it is impossible to fix the genus 1 . 



The old name of Entomostracites was also applied by Wahlenberg to the genus Trinucleus, 

 one species of which is copied from that author into Brongniart's work, PI. 3. f. *J., under 

 the name of Entomostracites granulatus. 



Loc. Michaelivood Chase, Tort worth ; Caradoc and Meifod Hills. 

 Asaphus Powisii (n.s.), f. 9. {a, b, c.) 



Head having a large round mamillated front, two prominent lateral divisions. Central lobe 

 of the body very wide, and separated by a raised margin from the lateral lobes, ivhich have 

 obtuse ends. Eyes composed of many minute lenses arranged in hexagons. Caudal portion 

 semicircular, and circumscribed by a broad band. (The eye is not seen in the larger figure, 

 hut is partially represented in f. 9 b.) 



I have named this splendid new species of trilobite after the noble family in whose demesnes 

 in Montgomeryshire it occurs. 



Loc. In the upper beds of the Caradoc formation at Cheney Longville, Salop, and in shale 

 of the same age at Welch Pool, Montgomeryshire. The fragment f. 9 b. was found by 

 Mr. Lewis and myself in the calcareous or upper bed of the Caradoc formation, on the banks 

 of the Onny, near Cheney Longville. 



The other portions figured were found by myself in "the trilobite dingle," Welch Pool, to 

 which I have already adverted, (see p. 217 and 303.) 

 IlLxEnus (Dalman). 



Illcenus f perovalis (n.s.), figs. 7 & and b. 



Elongated oval form ; cetitral lobe of the body slightly prolonged into the caudal portion. 

 Blind f 



From its equally balanced extremities, this animal was supposed to belong, as mentioned 

 p. 215., to the genus Isotelus. It appears, however, to differ from every published species, 

 though it most nearly approaches Illcenus, Dalman, from which, however, it must differ if 

 really blind. 



Loc. Flanks of the Corndon (or Cornden) mountain near Shelve, on the borders of Salop 

 and Montgomery , where I found it in Lower Silurian Rocks much altered by igneous action. 

 Other trilobites from this tract are figured in PI. 25. figs. 4 & 5. 

 Asaphus duplicatus, nob. PI. 25. f. 7- 



Body 13 to 14 ? ribs, central lobe very small and prolonged to a sudden termination in the 



1 A small elongated but mutilated Calymene, distinct from C. Blumenbachii and nearly resembling C. Tristani, 

 Brongn., was found at Cefn Rhyddau near Llandovery, by Mr. W. Williams, and at Cefn-y-garreg ; also near 

 that place by myself, in both instances in Lower Silurian Rocks. 



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