62 SILURIAN TRILOBITES. 



C. capite 1^ unciam lato,longo, convcxis.nmo, articulato. Glabella subcglindrica, antice 

 latior, lobo frontali semicirculari, supremo lineari, secundo subtriangulari, basalibus trigonis 

 mbplanis lovgis, fere medium glabellce attingentibus, cervicali triangulate late. Gena 

 declives eonvexa, profunde scripta et marginata, spinis divergent/bus brevibus. Oculi 

 hand ad glabellam appositi, ad lobum medianum retracti. Junior cum senioribus forma 

 convenit 



When described for the Decades of the Survey, we possessed but one or two imperfect 

 heads. Now we have excellent specimens from Mr. Pengelly's cabinet. These show the 

 true shape of the glabella and the fixed — but not the free — cheeks. Lest there should be a 

 mistake, I have only given the characters from the British specimens, which differ from 

 Minister's figure in having a shorter glabella, with the terminal lobe especially not so long, 

 (Minister's figure has it almost circular, which is not likely), and narrower cheeks ; and 

 that author also describes his species as having great wings, or free cheeks, like those of his 

 C. propinqua. If his figures were quite trustworthy, 1 our species must be distinct, 

 and I should, in that case, propose the term C. Pengellgi for this fine Devonian 

 fossil. 



Our species has the head eleven lines long, by one and a half inch broad, the glabella 

 occupying the whole length, and regularly tapering from a breadth of eight lines in 

 front to six at the base. The forehead-lobe is semicircular, and occupies just as much 

 length as the remaining lobes, excluding the broad, subtriangular neck-segment. The 

 middle and upper lobes are separated by complete, deep, transverse furrows, and are of 

 equal width, the upper pair forming a transverse linear band, the middle pair also trans- 

 verse, but rudely triangular where they abut on the truly triangular basal lobes. These 

 reach far across, and are separated by a depressed space barely equal to half the width of 

 one of the lobes. The basal lobes are less tumid than the rest, the upper lobe more so 

 than the middle one, and the forehead-lobe more tumid than any. These proportions are 

 maintained in young specimens (see fig. 8). The surface of the glabella is coarsely 

 tubercular. 



The cheeks, separated by deep axal furrows, are convex, rather steeply declining, their 

 full width equal to that of the glabella at its base, and the position of the eye-line is such 

 that the free cheek is not above one third the length of the head (in Minister's figure it 

 is much more), with a strong thickened margin and marginal furrow, within which the 

 cheek is deeply punctured, and appears tubercular ; the head-spines diverge, and are short 

 and narrow. 



The profile-view (fig. 7, b) gives a good idea of the convexity of the head. 



1 Count Minister gives us good reason to distrust his accuracy, for he figures the lower glabella- 

 furrowe as continuous across, instead of bending down to join the triangular basal lobes. This is im- 

 possible. He has represented his so-called C. Stembergii, and C. propinqua, which are probably but one 

 .species, as having these broad wings, but there is an appearance of error about all his figures. 



