BRITISH FOSSILS. 



Decade II, Plate I. 



PHACOPS CAUDATUS. 



[Genus PHACOPS. Emmerich. (Sub-kingdom Articulata. Class Crustacea. Order 

 Entomostraca. Family Trilobitse.) Eyes largely facetted ; facial suture ending on the 

 outer margin ; thorax 11 jointed.] 



[Sub-genus Dalmannia. Depressed ; pleurae pointed and bent back at a distant fulcrum ; 

 glabella not inflated, with three lateral lobes ; facial suture within the edge in front ; head 

 angles long-spined ; hypostome obtusely pointed ; tail with a many-jointed axis, and 

 without lateral spines.] 



Diagnosis. P. (Dalmannia) fronte angulato ; oculis maximis pyra- 

 midatis, e sulco glabellari basali ad tertium et supra extensis ; pleuris 

 recurvis, fulcro ad dimidium ; caudce apice mucronato, axi 11-12 annulato^ 

 costis lateralibus 7, rarius 6, arcuatis, duplicatis, ad marginem Icevem 

 ahrupte terminatis. 



Synonyms. — Var. a. Vulgaris. — Fronte capitis angulato ; apice caudce 

 brevimucronato. — Plate I., figs. 1 to 12, and fig. 15. 



Trilobus caudatus^ Brunnich (1781), Kjobenh. Sellsk. Skrifter. Nye 

 Samml., vol. i., p. 392. Asaphus caud., Brongniart (1822), Crust. Foss., 

 t. 2, f. 4 (not 3, f. 9). Trilob. caud., Schlotheim (1823), Nachtrage, 

 35. 11. Asaphus caud., Dalman (1826), Palead., t. 2, f. 4. Green 

 (1832), Monogr. Trilob. N. Amer., cast 17. Buckland (1836), Bridgw. 

 Treat., pL XLY., f.9-11. IVIurchison (1837), Sil. Syst., pi. 7, fig. 8 a. 

 A. tuberculato-caudatus, ib., fig. 8 b. A. caud, and A. tuber culato-caud., 

 ]\IiLNE Edwards (1840), Crust. 3, 308. P. caud., Burmeister, Org. 

 Tril., t. 4, f. 9. Ray edition (1846). 



Var. y8. Longicaudatus. — Plate I., figs. 13, 14. — Axi angustiori, fronte 

 capitis cauddque longimucronatis, 



Trilobite with caudal process, Parkinson (1811), Organic Remains, vol. 

 iii., t. 17, f. 17. Asaphus longicaudatus, JMurchison, Sil. Syst., pi. 14, 

 figs. 11 to 14. JMiLNE Edwards, Crust. 3, 308. Phacops mucronatus, 

 Burmeister, Org. Tril., 113 (exclude all synonyms except JMurch.). Ray 

 edit., 95. \Phac. longicaud., Rouallt (1847), Bull. Soc. Geol. Fr., 2nd 

 Ser., 4, 320?]. 



Description of Var. — Four or five inches long; ovate; length as 

 to width varying from 10 • 6 to 8 J * 6 ; thorax longer than either head or 

 tail ; the latter about equal to the head, excluding the produced mucro ; 



[ii. i.] 2 b 



