3IO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



Corynexochus Matthew, 1899, Trans. Royal Soc. Canada, 2d ser., Vol. 5, 

 Sec. 4, p. 47. (Mentions genus and describes new species, C. romitigeri.) 



Corynexochus Lindstrom, 1901, Kongl. Sven. Vet.-Akad. Handl., Vol. 34, 

 No. 8, p. 22. (Lists genus in connection with development of " facial 

 ridge.") 



Corynexochus Gronwall, 1902, Danmarks Geol. Unders. Vol. 2, No. 13, 

 Bornholms Paradoxideslag, p. 136. (Names C. spinulosus Angelin as the 

 type and describes and illustrates the cranidium and associated pygid- 

 ium ; also describes and illustrates a new species, C. bornholmiensis.) 



Karlia Walcott, 1916, Smithsonian Misc. Coll., Vol. 64, No. 3, p. 223. (De- 

 scription reprinted from 1889 and type species illustrated.) 



Description. — General form of dorsal shield longitudinally oval, 

 moderately convex. Cephalon transversely semicircular with genal 

 angles rounded or extended backward in sharp spines ; marginal 

 border narrow, rounded or slightly flattened; in front widening 

 tov/ard the genal angles ; posterior margin and occipital ring defined 

 by a well-marked furrow. The facial sutures cut the anterior margin 

 so as to leave a small antero-lateral space next to the glabella and 

 curve inward to the base of the eyes, over which they arch ; back of 

 the eyes they extend obliquely outward and backward nearly to the 

 genal angles. 



Glabella elongate, expanded anteriorly and contracting gradually 

 in width from the little pits in which the dorsal furrows terminate 

 anteriorly ; marked in varying degrees of strength by two or three 

 pairs of rather short lateral furrows, the posterior two pairs of which, 

 if present, slope obliquely inward and backward. 



Occipital ring clearly defined, broadly rounded and low, or narrow 

 and high, with or without a median spine. On Corynexochus senec- 

 tus it is without a spine (pi. 56, fig. i). Corynexochus spinulosus 

 has a small node at the center (pi. 55, fig. i), and Corynexochus 

 bubaris has a rather strong occipital spine (pi. 56, fig. 3c). Occipital 

 furrow varying in width and depth, but distinct and clear in all 

 species. 



Fixed cheeks moderately convex, with large, roughly triangular 

 posterolateral limbs, narrow to medium width of central section, and 

 small antero-lateral limbs ; palpebral lobes one-sixth to one-fourth 

 the length of the cranidium with a narrow palpebral ridge coming 

 around the eye and extending obliquely inward and forward across 

 the fixed cheek to the dorsal furrow beside the glabella. Free cheeks 

 narrow, usually with a genal spine, but may be rounded posteriorly 

 as in C. minor (pi. 55, fig. 6). 



