BRITISH FOSSILS. 



Dec ade XI. Plate IX. Figs. 1^5. 



PHAGOPS (TRIMEROCEPHALUS) L.ffiVIS. 



[Genus PHACOPS. Emmrich. (Sub-kingdom Articulata. Class Crustacea. 

 Order Trilobita. Family Phacopidaj.) Eyes largely facetted ; facial suture ending on 

 the outer margin ; thorax 11 -jointed.] 



[Sub-genus Trimerocephahis. Form compact. Glabella inflated and expanded 

 or wards, the lobes, except the basal ones, obscure. Eyes very small, of few large 

 lenses (often lost by abrasion) or absent. Head angles not spinous. Facial sutures 

 soldered. Thorax v/ith pleura) all rounded. Tail small, of few segments, with even 

 border, and not at all produced.] 



DiAGNOSi?^. P. ( Tinni.) ccecns. late ovatus IcBvis, glabella latissimd, 

 brevi, genas subsphericas trigonas SKperintcndente ; lobis basalibus minutis 

 distinctis. Thoracis axis angustns^ ftilcro pleurarum axin approximato, 

 sidcoque brevi. Cauda latissima brevis, axi longo, 3-annulato^ lateribus 

 A-stilcosis, margini nulla. 



Synonyms. Trinucleus IcBvis, Munst. Beitr. Heft 5, t. x. fig. 6 (1842). 

 Calymene Icevis, Phill., Pal. Foss., pi. 55, fig. 250 (1841), (not Cal. IcBvis, 

 MuNST., 1. c. t. V. fig. 4). Asaphus or Trinucleus, Sowerby, Geol. Trans., 

 2nd Ser., vol. v. pi. 57, fig. 30 (1840). Trinierocephalus Icevis, McCoy, 

 Ann. Nat. Hist. vol. iv. p. 404, woodcut (1849). Ibid, Synopsis Woodw. 

 IMus., p. 178 (1851). Salter, Palasont. Society, Monogr. (1864), p. 16, 

 pi. 1, figs. 5, 6, 7. 



It would perhaps be better if a new name were bestowed upon 

 tbis- species. It is clearly enough the Trinucleus Icevis of Miinster, 

 and that fossil belongs to Phacops. But the Phacops (Calymene) 

 Icevis of Miinster is quite another thing, and typical of another sec- 

 tion, of the genus ; and if the ]^^^ r were a good species, and not a 

 mere synonym of P. granulaius, as I believe it to be, it would be 

 imperative to change the name, and I would then propose the term 

 P. trinucleus for this species. At present it had better stand as 

 P. Icevis. 



[XI. ix.] 11 I 



