3l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



semicircular in the large forms, which are perhaps accidentally de- 

 pressed by compression. 



" The glabella has, much more, even, than in all the other species 

 of the genus, the clavate form described by authors. Very narrovv^ 

 in the low^er part and often compressed at the base, it expands 

 abruptly, toward the middle of its height, into a regular oval, some- 

 times a complete circle. It has its dorsal furrows accentuated and 

 stands out in relief above them ; there is no trace of lateral furrows ; 

 the occipital furrow is hardly distinct ; but below it, however, the 

 occipital ring appears, very narrow, convex, and rounded, and termi- 

 nates in a spine quite apparent to the naked eye on certain specimens. 



" The facial suture becomes detached at two-thirds the height of 

 the glabella, at the point where the convexity of the latter is most 

 marked, and descends toward the base by an almost straight line, 

 sometimes slightly convex, so as to give to the fixed cheeks a very 

 narrow, triangular form. The very small eyes are scarcely visible. 

 The free cheek is always lacking. Thorax unknown. 



" The pygidium has the form of a semicircle, generally a little 

 depressed ; the axis, much in relief, well marked, is narrow and 

 long, without quite reaching the lower margin ; we count under the 

 lens five and perhaps six rings. The lateral lobes have the first pleura 

 apparent ; the others are more effaced and scarcely visible. 



" The test is without punctation. 



"Analogies and differences. — Corynexochus delagei is by far the 

 most specialized of the species which I am describing ; it constitutes 

 the only Corynexochus known up to the present from the lower beds 

 of the Acadian ; it is very clearly distinguished at first sight from 

 Corynexochus spiniilosus, Ang. and from Corynexochus romingeri 

 Matt., which belong, in Scania [Skane] and at Mount Stephen, to the 

 beds with Paradoxides forchhammeri Ang. of the upper Acadian. It 

 is nearer Corynexochus hornholmiensis Gronw. from the middle 

 Acadian of Borregaard, in the island of Bornholm ; but it is distin- 

 guished from that by the rounded form of the top of the glabella, by 

 the great convexity of the base of the dorsal furrows, by the com- 

 plete absence of lateral furrows, and by the efifacement of the rings 

 and the pleurae of the pygidium." 



M. J. Miquel very kindly sent me a specimen of the cranidium and 

 one of the pygidium, which are illustrated on plate 55, figures 3, 3a. 

 These have a more striking resemblance to the Newfoundland C. 

 minor Walcott (pi. 55, fig. 6) than to the geographically nearer 

 C. spinulosus Angelin and C. hornholmiensis Gronwall. 



