4G SILURIAN TRILOBITES. 



about two inches; the general form that of a pointed arch; the glabella narrowed,long-oblong, 

 not much broader in front than behind, the forehead-lobe as long as the rest of the glabella 

 (including the prominent neck-segment), and almost round. The side-lobes are very strong, 

 and divided by deep, radiating furrows, deepest and strongest inwards, and reaching far 

 towards the centre. The upper lobe trigonal, not greatly larger than the mid-lobes ; the 

 basal lobe narrow, almost linear externally (and clavate in the cast). The whole glabella 

 covered by coarse tubercles and fine granules intermixed. 



The eyes are large, reniform, elongate, compressed laterally instead of longitudinally, and 

 placed in advance of the centre of the cheek, half their own length from the neck-furrow, 

 and touching the glabella in front. The cheeks curve steeply down, are scrobiculate, not 

 tubercular, margined nearly all round by the narrow furrow, and provided with head-spines 

 half as long as the glabella. 



The facial suture curves largely forward outside the eye, and cuts the margin about 

 half-way up the cheek. 



We have no body-rings. The tail is broadly triangular, pointed below, but not pro- 

 duced into any mucro, and with a very narrow equal margin. The conical and very 

 convex axis nearly reaches the tip, annulated all the way down, and has about twelve sharp 

 rings. The sides are strongly radiated ; nine or ten strongly duplicated ribs running on 

 each side to the narrow margin. The intermediate furrows are straight at their origin 

 and terminations, and at the latter point they are so deep as to make the margin 

 pretty strongly undulate. 



Locality. — Caradoc slate of Coldwell, Westmoreland ; in beds over the Coniston 

 limestone. [Brit. Mus. Mus. P. Geology. Woodwardian Museum, &c] 



Puacops (Odontochile) mtjcroinatus, Brougn. ? PI. IV, figs. 11, 12. 



[Entomolithus, Linnoeus. Iter Vestrogoth. p. 88, cum fig. 1/47. 



Entomostracites caudatus, Wahlenberg. Nova Acta Reg. Soc. Upsal, torn, viii, 



p. 28, t. ii, fig. 3, 1821. 

 Asaphus mucronatus, Brong. Crust., p. 24, t. iii, fig. 9, 1822. 



— — Dalman. Palseadse, p. 236, t. ii. fig. 3, a, b, 1826. 



— — Hisinger. Lethsea Suecica, p. 13, 1837. 

 Phacops — Emmrich. Dissert. (1839) ; Neues Jabrbuch, 1845. 



' — — Angelin. Palseont. Suecica, tab. viii, fig. 1,2, 1852.] 



— — Salter. Decade VII, Art. 1, p. 12, 1853. 



P. triuncialis et supra. Glabella convexa, antice parum dilatata, utrinque lobis tribm 

 subaqualibus transversis, sulcis longis satisque prqfundis sese separatis. Cauda triangularis 

 acuta ; axe convexo limbo piano hand cequali, in annulos 9 et appendiceal diviso [appen- 

 dice in apicem caudce brevimucronalum percurrenle ?~\ ; lateribus costis 8 plants, sulcis 7 



