BRITISH FOSSILS. 



Decade II. Plate VI. 

 OGYGIA BUCHII. 



[Genus OGYGIA. Brongniart. (Sub-kingdom Articulata. Class Crustacea. Order 

 Entomostraca. Family Trilobitse.) Eyes large, smooth ; facial suture cutting the pos- 

 terior margin ; no rostral shield or vertical suture ; hypostome entire ; body rings 8 ; 

 tail large.] 



Diagnosis. O. ovalis, glabella angustd utrinque quinquesulcatd ; oculis 

 ad medium capitis ; suturd faciali ad frontem marginali ; spinis posticis 

 brevihus ; hypostomate obtuse acuminato ; thoracis axi bis pleura angustiore ; 

 caudcB axi longo abrupto ; sulcis lateralibus 1 2 duplicatis^ prope marginem 

 angulatim deflexis. 



Synonyms. Llhwyd (1698), Philosopb. Transact., vol. xx., 279, tab. 

 addit., f. 15. Baglossa curta strigosa, ib., Ichnograph. Brit. (1690), Epist. 1, 

 t. 22, f. 2. Trilobite from Llanelly, Parkinson, Organ. Rem. (1811), 

 V. iii., t. 17, f. 13. Asaphus De Buchii, Brongniart, Crust. Foss. (1822), 

 t. 2, f. 2. Trilob. Be Buchii, Schlotheim, Nachtr. (1823), ii., 34 

 (excl. the locality, " Norway.") Asaph. Buchii, Dalm. Palead. (1826), 68. 

 J. D. C. SowERBY, in Loudon's Mag. Nat. Hist., 1829, vol. ii., f. 27. 

 BucKLAND (1836), Bridgwater Treatise, t. 46, f. 7. Murchtson (1837), 

 Sil. Syst., t. 25, f. 2. Quenstedt, Wiegm. Archiv. (1837), vol. iii., 1, 346. 

 Emmerich, Dissert. (1839), 28. Milne Edwards, Crust. (1840), 3, 309. 

 Burmeister, Org. Trilob. (1843), t. 1, f. 2, [facial suture wrongly figured.] 

 Ray edition (1846), p. 59. Corda, Bohm. Tril. (1847), t. 4, f. 39 [bad.] 



Junior. Trinucleus? asaphoides, Murchison, Sil. Syst., t. 23, f. 6. 



Milne Edwards, Crust., v. iii., 333. 



Description. — Length occasionally near seven inches, generally three 

 or four ; proportion of length to breadth from 6:5 to 6 : 4, a consi- 

 derable variation. General form a broad depressed oval, the head 

 nearly semicircular and as long as the thorax, the tail semi-elliptical 

 and longer than either ; glabella at its base occupying one-fourth or less 

 of the width of the head, broader and more convex above, and a little 

 pointed in front ; it extends nearly to the front margin, and is marked, 

 a little within each side, by a longitudinal depression, which is curved 

 with the convex side inwards. Along this hollow lie five pits, v^hich 

 represent the glabella furrows ; the basal one is the neck furrow, that 

 [ii. vi.] 2 F 



