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SILURIAN TRILOBITES. 



H. magnus, 7-9 uncialis ; capite latissimo, longitudine hand dimidium latitudinis attin- 

 gente ; f route late iruncatd redd. Glabella sub quad rata, sulcum obscurum marginalem frontis 

 petens, ad basin latitudini gena? convexa cequalis. Oculi post medium capitis positi, sub- 

 remoti. Sutura facialis margini postico parallela. 



Heads only are known of this splendid species. It must have grown eight or nine 

 inches long, and has, strangely enough, been quoted by M'Coy, in the Cambridge Col- 

 lection, not only as H. bisulcatus, from which the wide transverse head separates it, 

 but even as Ascqjhus Poivisii. 



The head is transverse, more than twice as wide as long, with so truncate a front as to 

 have that edge parallel to the hinder one. The front margin has a slightly concave furrow 

 within it, up to which the glabella reaches. This is subquadrate, its sides a little con- 

 tracted, its base not much the widest, but still broad ; the front emarginate, and defined 

 by the front furrow, as before stated. 



The cheeks are as wide as the base of the glabella, convex, almost gibbous at the eyes, 

 which are somewhat remote. The facial suture curves out boldly from the eye, parallel to 

 the hinder margin, and cuts the outer edge in advance of the blunt angle. The neck-furrow 

 is strong in the cast, and reaches all across ; it is sharp under the glabella, and broader 

 and blunter beneath the cheeks, separating there a broader and more convex neck-seg- 

 ment than that beneath the glabella. 



The eyes, in large fine specimens in the Cambridge Museum (fig. 25) show a small 

 eye- lobe. I only know two specimens ; and yet I expect the species to be a common 

 one, and its body and tail-portions should be looked for in the following — 



Localitg. — Caradoc Slates of Ravenstone Dale, Westmoreland. Both specimens 

 are in the Woodwardian Museum. 



Homalonotus Edgelli, n. sp. PL X, fig. 11 (and fig. 10?) 



II. minor, H. bisulcato simillimus, nisi caudd {solum cognotd) angustiore, axe angusto 

 conico, S-annulato, a lateribus declivibus bene sejuncto. Costa laterales 7 plana, Jiaud 

 interlineata, ad margiuem angustum fere tractce, duo superiores profunde exarata. 



It is possible that the small head (fig. 1 0) from Horderley may belong to this species, 

 but I only describe the tail. 



A neat species, which has so strong a resemblance to the preceding that it may be 

 difficult to distinguish it when more specimens are found ; and it may possibly, though, 

 I think not probably, be the S form of H. bisulcatus. Nevertheless the proportions 

 are so different that we cannot well mistake it. The tail is very convex : the axis is 

 decidedly narrower, — hardly more than half the breadth of the side-lobes, and the ribs 

 fewer : and though these are only differences of proportion, and we must wait for better 

 materials to be certain about the species, they are probably sufficient in a genus like the 

 present, where the forms are so closely allied. 



Localitg. — Caradoc beds. Acton Scott, Shropshire. Mr. H. W. Edgell's cabinet. 



