194 Dr. Ivor Thomas — Trilohite Fauna of Devon and Cornwall. 



The fairly tumid glabella is markedly pentagonal, witli a low- 

 curvature on the anterior margin, and is bounded by strong dorsal 

 furrows enclosing an angle of circa 50°. Its length in our specimen 

 is 8 mm., and the greatest breadth near the frontal extremity is 

 approximately 7 mm. The basal furrow is rather shallow at the 

 centre, but deepens where it joins the above-mentioned dorsal furrows. 

 The basal ring is slightly elevated and fairly broad, while the 

 adjacent occipital furrow is shallow where it bounds the basal ring, 

 and becomes deeper towards the cheek margins. 



The cheek-areas are ti'iangular, elevated, and fall gradually towards 

 the glabella, but steeply outwards towards the marginal border. No 

 trace of eyes is to be seen. 



Locality and Horizon. — This specimen was obtained in the Upper 

 Devonian purple and green slates of Daymer Bay, Cornwall. Mr. Dewey 

 informs me that these beds are much overthrust and contorted on the 

 south side of the bay, where they are overlain by sand. On the north 

 side they are more exposed, and have been found to be highly 

 fossiliferous in a low reef of rock near the end of the lane leading 

 from Trebetheric to the sands. West of this lane and by the first 

 hedge along the cliff, a fault, east and west in direction, throws down 

 the purple and green slates, and brings into sight black shaly slates 

 full of pyritous casts of cephalopods and lamellibranchs. The 

 described trilobite was found on the foreshore, 50 yards west of the 

 above-mentioned hedge, in association with pygidia of Phacops latifrons 

 (Bronn), Teniaculites cf. tenuicinctus, F. A. Koemer, and poorly 

 preserved brachiopod remains. The black slates have yielded Tornoceras 

 sp., Ortlioceras commufatum, C. G. Giebel, BucMola cf. semiimpressa, 

 Drevermann, and a small form referable to Modiella pygmcea (Conr.). 



Remarhs. — Owing to long exposure to the sea the specimen is not 

 as well preserved as could be desired. The frontal lobe of the glabella 

 has been somewhat worn anteriorly, and parts of the marginal border 

 are destroyed. The same specimen has been referred to in a former 

 paper under the name Phacops [Trim.) cf. anophthalmus (16, p. 100). 



The name anopMliahmis was given by Professor Freeh (4, p. 270) 

 to Phacops cryptophtlialmus of F. Boemer from the Upper ])evonian of 

 Kielce, Poland (13, p. 674, pi. xiii, figs. 6, 7), and of Tietze (18, 

 p. 126, pi. xvi, fig. 1), from the Clymenienkalk of Ebersdorf (not 

 cryptoplithalmus of Emmrich). Professor Giirich described the same 

 form under the name Trimerocephalus iyphlops^ no v. nom., from the 

 middle Upper Devonian of Kadzielnia, Poland (6, p. 359, pi. xv, fig. 7). 



Phacops (Tkime-rocephaltjs) aff. cryptophthalmtjs, Emmr. (as 

 interpreted by Giimbel). PL YII, Figs. 2, 3. 



DescriiAion. — The general contour of the cephalon is semicircular, 

 with a practically straight posterior margin and a breadth almost 

 twice the length. The whole surface is covered with small granules. 



The somewhat flattened glahella is pentagonal in outline, and is 

 bounded by deep dorsal furrows enclosing an angle of circa 80°. The 

 posterior part has a deep basal farrow and a fairly elevated, convex, 

 basal ring. The occipital ring is imperfectly preserved, but appears 

 to have been as broad and elevated as the basal rinj*. 



