Silurian.] PALEONTOLOGY OF VICTORIA. [Trihhites. 



is minutely granular. Owing to the abrasion of tlie surface of the 

 glabella, I cannot be certain whether segmental furrows occur or 

 not. 



Only one British species of this genus (my F. lafifrons) has ever 

 been quoted from Lower Silurian strata, and I cannot help thinking 

 there may be some error in the age assigned to the Irish locality, 

 Egool, Mayo, as I have found the same species in England only in 

 Upper Silurian rocks. The 36 species of Proetus given by Barrande 

 are all Upper Silurian, and so few forms, and these abnormal, have 

 been found in older rocks, that the present species must be taken to 

 support the reference of the bed in which this species is found to 

 the Upper Silurian. 



Rare in Wenlock shale of Broadhurst's Creek, east of Kilmore, 

 BMS. 



Explanation op Figures. 

 Plate XXII. — Fig. 10, entire trilobite, natural size. Fig. 10a, ditto, magnified. 



Plate XXII., Fig. 11. 

 LTCHAS AUSTRALIS (McCoy). 



[Genus LICHAS (Dalmann). (Snb.-kingd. Articulata. Class Crustacea. Order Ento- 

 mostraca. Tribe Phyllopoda. Fam. Trilobitida;.) 



Gen. Char. — Bod;/ OTate, Tery fiat ; .<iiirface granulated ; head semicircular ; glabella large, 

 semi-oval, with one long segmental furrow curving inwards and downwards from the upper 

 third of the glabella on each side, nearly to the neck-furrow, partially enclosing two large oval 

 spaces, and close to the ends of the neck-furrow, one or two posterior ])airs of fun'ows enclose 

 one or two small trigonal lobes on each side ; neck-segment broader than the base of the glabella ; 

 cheeks small ; e;/es moderately large, reniform ; ei/e-line cutting the outer margin in front of the 

 angles ; thorax of 10 segments ; pleura flat, falcate, each with a fine slightly sigmoid pleural 

 furrow, not reaching the margin ; pt/gidium serai-oval, axis usually undefined below, the lateral 

 furrows instead of encircling the end, converge about the middle, and diverge again towards the 

 posterior margin, which they do not reach; two short segments at the anterior convex p,art ; 

 side-lohes fiat, of two broad falcate ribs on each side, projecting beyond the margin, each with a 

 fine mesial duplicating groove ; niitldle-lohe semi-elliptical, pointed, a small divisional line coming 

 off from the middle of the dorsal furrow on each side, curving outwards and downwards towards 

 its extremity, so as jiartially to include an oval space on each side.] 



Description. — Width across plabella and middle of anterior lateral lobes, 5tlis 

 of the leng'th of the head, including- neck-seoment ; middle portion of g-labella 

 tumid, broadly rounded in front, rather narrowed in the middle by the regular inward 

 curvature of the anteiior segmental furrows ; anterior segmental lobes ovate, tumid j 



[ 18 3 



