BEITISH FOSSILS. 



Decade VIL Plate VII. 



TEINUCLEUS LLOIDII, 



[Genus TRINUCLEUS* (Llhwyd) Murchison. (Sub-kingdom Articulata. Class 

 •Crustacea. Tribe Trilobitae.) Head of one piece, the facial sutures being soldered ; the 

 margin expanded into a hollow fringe, with several rows of perforations ; eyes minute, 

 sometimes absent ; hypostome convex, elongated, without furrows. [Bark.] ; body six- 

 ringed, fewer, 0-6, during the metamorphosis. Cryptolithtts, Green.] 



[Sub-genus Trinucleus. Eye line and ocular tubercle obscure ; glabella lobes indistinct.] 



Diagnosis. T. rotundus planus, testa tenui ; glabella pyriformi ahbre' 

 matd nec genas excedente, suhcarinatd ; cervice spinifero ; fimbria margi- 

 nali concavd, punctis minutis radiatis crebris in ordines 6 concentricos 

 €ollocatis ; alis magnis triangulatis, caudam attingentibus, spinis longis 

 parallelis [nunc truncatis inermibus ?~\ ; cauda concava truncata, sulcis 

 lateralibus. 



Synonyms. Trinucleus Lloydii, Murchison (1839), Silurian System, 

 tab. 23. fig. 4. EiiMRiCH (1839), Dissert., p. 53. Milne Edw. (1840), 

 Crust., vol. iii. 331. T. granulatus (Wahl.), Burmeister, Trilob. (1843), 

 66; 2d ed. (1846), p. 57. Salter (July 1847), Quart. Geol. Journal, 

 p. 254. Phillips and Salter (June 1848), Memoirs Geol. Surv., vol. ii. 

 pt. 1. p. 240. 



Var. /3. Corndensis. — angulis posticis capitis brevioribus, figs. 2 and 6. 



This elegant species is abundant in Carmarthenshire and in the 

 mining district of Shropshire, the only, localities in which it has yet 

 been observed ; for although it has been supposed identical with a 

 species common in Sweden, it is apparently quite distinct, and it is 

 here figured as well to clear up this point, as because it is an excel- 

 lent illustration of the remarkable genus to which it belongs. 



Description. — Length about three quarters of an inch, and width 

 one inch. General form flattish, especially behind, — circular, or, 

 excluding the fringe, a very broad oval, and with long spines 

 directed straight backwards and reaching far beyond the tail. 



* Erom tres, three, and nucleus, in allusion to the three convex portions of which the 

 head is composed. 



[vil. vii.] 7 o 



