CONTRIBUTIONS TO PALiEONTOLOGf. 149 



CONOCEPHALITES MINOR (Shumard). 



PLATE VIII. PIGS. 1-4. 

 Conocephalites minor : Shumard, Trans. Acad. Sciences of St. Louis, Vol. ii, p. 105. 



*' Very small. Glabella well defined by linear dorsal furrows, 

 " subcircular, much elevated above the cheeks, regularly con- 

 " vex, slightly longer than wide, marked on either side with 

 *' two short deep lateral furrows, which are directed obliquely 

 " backwards, and reach not quite one-third the distance across : 

 " neck-furrow linear, distinctly but not deeply impressed, si- 

 *• nuate, arched forward in the middle ; neck-segment short 

 " triangular, gently convex, not elevated, posterior angle ter- 

 " minating in a delicate acicular spine which is prolonged 

 " backwards, its length unknown; front margin narrow, convexj 

 " cheeks rounded, having very delicate ocular ridges, which 

 *' pass from the eyes in a short curve to reach the glabella a 

 " short distance in advance of the anterior glabellar furrow. 

 " Length of head, 0*10 of an inch; length of glabella, 0'08.'^ 



Among a large number of specimens in my collection, which I 

 have referred to this species, there are some varieties of form. 

 A single specimen of the head, destitute of cheeks, which was 

 kindly sent to me by Dr. Shumard, from near the mouth of Black 

 river, has a more rotund forni, and the glabella is proportionally 

 shorter than in specimens from Trempaleau, before regarded as 

 undescribed, but wdiich I have now identified with the species of 

 Dr. Shumard. The sandstone of the Black -river locality is of 

 somewhat different character, finer and more compact; and the 

 difference in form may be due only to physical conditions. 



In the Trempaleau specimens the glabella is ovoid and very 

 gibbous ; the width and length to the occipital furrow about as 

 three to four, varying slightly in different specimens, some of 

 which are proportionally longer. The lateral furrows reach about 

 one-ihird across the glabella. The anterior furrow is short and 

 slightly oblique : the middle furrow is more deeply impressed ; 

 and the posterior furrow is more oblique and deeper, separating 

 the posterior lobe so that sometimes it appears like an ovoid tu- 

 bercle. The occipital furrow is either direct or a little arched 

 forward, sharply impressed : the occipital ring is short, triangular, 

 and extended posteriorly into a slender sharp spine, which, in- 

 cluding the segment, is about as long as the glabella. The dorsal 

 furrow is strongly defined, limiting the glabella as distinctly in 

 front as at the sides. The fixed cheeks are narrow, convex or 



