[MATTHEW] STUDIES ON CAMBRIAN FAUNAS 47 



a shorter eye-lobe. Such differences might exist between the larval and 

 adult shield of the same species. 



Conocephalites (sens, strict.) is a type of the Upper Cambrian, though 

 one species, C. ornatus, Brogger, is known from the Paradoxides Beds. 



COEYNEXOCHUS, Angelin, 1854. 



In his Palseontologia Scandinavica, Angelin described a genus of 

 small trilobites upon the basis of two species, one Cambrian and the other 

 Ordovician. As the second is represented only by a pygidium and re- 

 ferred doubtfully to the genus it may be disregarded. Taking the Cam- 

 brian species only, we find that in this the pygidium is referred to the 

 head-shield with an interrogation mark. Corynexochus then is narrowed 

 down to the head-shield of this Cambrian trilobite, and we find in it a re- 

 markable resemblance to a species described by Eoeminger from the 

 Mount Stephen fauna. This is Menocephalus Salteri (Bill.) Roem. 



Corynexochus Roeminqeri, Matt. n. sp. (PI. II., fig. 3.) 



Menocephahis Salteri, (Bill.) Roem.,Proc. Acad. Nat. Sci., Philad'a., 1SS7, Pt. i.,p. 16, 



PI. i., fig. 6. 

 [Knrlia stephenensis. Wale, Proc. U. S. Nat. Mu.s., 1888, p. 445; no figure, (referred 



to Roeminger s M. Salteri, is not this species, but probably Borypyge 



Dawsoni. (See below.) ] 



On referring to Billings's figure and the description of M. Salteri, I 

 agree with Mr. Walcott that the Mount Stephen species above cited is not 

 the same, being separated both by the form of the glabella and cheeks and 

 by the projecting anterior marginal fold. Dr. Eoeminger considered the 

 Mt. Stephen species to be closely related if not identical with this species, 

 and gave a figure with the following description : — 



"The head deprived of the movable cheeks, bears a large glabella, 

 considerably dilating in front, with three distinct lateral furrows. The 

 thoracic ribs are deeply excavated in the centre, and the adjoining 

 margins of every rib pi'oject as high ridges, with a dividing line along the 

 crest. The annuli composing the pygidium are rather obsolete, but four 

 sharp furrows, spreading from each side of the rachis, indicate its com- 

 position of at least four anchylosed segments. 



" Size. — The specimen [showing the whole shield except the movable 

 cheeks] has a total length of 16 mm. ; length of head 6 mm.; length of 

 thorax with seven segments also 6 mm. ; length of pygidium 4 mm." 



I may say in reference to this description, that in the three lateral 

 furrows of which Eoeminger speaks, he appears to have included the 

 occipital furrow, for only two glabellar furrows appear in his drawing. 

 His example was a mould ; on the outside of the test when preserved, 



