Siluriau.} PAL^ONTOLOGT OF VICTORIA. [Trilohites. 



by our figure, and also the same variation in projection of the 

 fi'ont. 



Abundant in the olive niudstones of (B" 18) Broadliurst's Creek, 

 E. of Kjlmore. 



EXPLAXATION OF FlGHRKS. 



Plate XXII. — Fig. 1, head, natural size, shortened by antero-posterior pressure. Fig. 2, eye 

 of second specimen, with eye-line or facial suture, n.atural size. Fig. 3, labrum or hypostome, 

 natural size (as in the English examples, the denticulation nf the lower edge usual in the sub- 

 genus Odontochile cannot be distinctly seen). Fig. 4, pygidium and six posterior segments of 

 thorax, natural size. Fig. 5, small perfect specimen of thorax and pygidium norm.al proportions, 

 natural size. Fig. 6, pj'gidium, natural size, of the very wide yariety. Fig. 7, pygidium, natural 

 size, of the n.irrow variety. Plate XXIII. — Fig. 7, head, n.atural .size, of narrow variety 

 probably from lateral pressure. Fig. 8, large head abnormally widened by antero-posterior 

 pressure, natural size. Fig. 9, natural size of large specimen of normal sh.ape of pygidium and 

 part of thorax. Fig. 10, pygidium with elongate posterior spine, natural size. 



Plate XXII., Figs. 8 and 9, and Plate XXIIL, Figs. 1-6. 

 PHACOPS (PORTLOCKIA) FECUNDUS (Bar.). 



Description. — Cephalic shield, nearly semicircular, greatest width at about ^ 

 of its length from the front ; glabella moderately convex, blunt, and only slig'htly 

 projecting- beyond the margin in front ; sides concave outwardly, converg-ing- at about 

 55° to the neck-furrow, which is very strongly marked, with the ends forming- marked 

 tubercles ; first pair of maxillary furrows short, but very deeply impressed, forminjy 

 a strong- tubercle on each side ; 2 anterior pairs of cephalic furrows scarcely per- 

 ceptible, short, fine, impressed lines ; cheeks with bluntly rounded angles, and 

 bordered by a very strong-ly defined thick limb or margin ; eyes very large, not as 

 prominent as the glabella, extending- from anterior angle of cheeks to a variable 

 point, always considerably in front of the posterior marginal sulcus (usually about 

 equal to the depth of the eye), usually about 18 vertical rows of coarse lenses in 

 each eye, and about 8 in each row (both numbers variable). Tliorax with the axis 

 or mid-lobe nearly as wide as the pleuree, each segment having a large strong-ly 

 marked tubercle at each sidej pleura3 broad, much bent down at the blunt outer 

 end, and divided by a very strong- deep diagonal pleural groove from the upper inner 

 corner. Pygidium nearly semicircular, convex, with a very strong-ly defined convex 

 axis of 10 distinctly marked segmental furrows, the anterior ones of which are tumid 

 at the outer ends, continuing the appearance of tubercles at sides of axis of thoracic 

 segments ; eacli side lobe bears 8 flat segmental ridges, marked by strong segmental 

 furrows, extending- rather more than g of the way to the margin, each costal ridge 

 divided along the middle by a distinct shallow impressed line or pleural groove ; 

 anterior margin with a strongly marked articular facet on each side. Surface covered 

 with a close fine granulation, with larger coarser conical grains or small tubercles 

 irregularl}' scattered through the smaller ones ; the granulation is strongest on the 

 glabella, about the same size but less distinctly seen on the cheeks, and scarcely 

 perceptible on the pygidium or elsewhere, and in only a few examples. Average 



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