150 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



rounded longitudinally, a little wider anteriorly, rarely showing 

 ocular ridges : the posterior limb is much extended. The frontal 

 limb is convex, narrower than the cheeks, marked by a sharp 

 groove, and terminated by an equally sharp, straight, narrow 

 border. The movable cheek is small, broadly triangular, with a 

 well-defined border which is prolonged into a short spine, and on 

 its inner angle supports a prominent oculiform tubercle. 



The caudal shields associated with this species are small, some- 

 what semicircular or paraboloid, with the axis prominent and 

 marked by about six rings. The lateral lobes show four distinct 

 ribs, which terminate in a narrow border. 



Well-formed specimens measure, from the neck-furrow to the 

 anterior limb, about 0"12 of an inch; the glabella being O'lO of 

 an inch in length, and about 0*07 of an inch in width. 



The figures 1, 2, 3, 4, are views of the glabella and fixed cheeks, a profile 

 of the same, a separated movable cheek, and a pygidium, which are all four 

 times enlarged. 



This small species is very common in the sandstone at Trempaleau, as- 

 sociated with C iowensis, Lingula ampla, Obolella? and Fugiunculus or 

 Theca. Dr. Shumard cites the Conocephalite8{Lonchocephalus)chippewaensis 

 as occurring in the same association, near the mouth of Black river on the 

 Mississippi. The original C. ( L.) chippeicaensis of Owen is cited by the 

 author as from thefoiuih or Marine-mills trilohite bed, while the C. minor 

 is in the loiuer trilobite bed. 



The following species of Conocephalites is from the Potsdam sandstone 



of New- York : 



CONOCEPHALITES MINUTUS. 



PLATE VIII. FIGS. 5, 6 & 7. 

 Conocephalites minutus : Bradley, American Journal of Science, Vol. xxx, p. 241, 1860. 



Head semicircular, somewhat straight in the middle of the front, 

 with the posterior angles of the cheeks produced into spines 

 which are more than half as long as the cheek-shields. 



Glabella very gibbous, ovate conical, a little longer than the 

 width at the base, slightly narrowed behind ; marked by three 

 pairs of glabellar furrows, the anterior ones being usually ob- 

 scure : occipital ring prominent in the middle, and produced 

 into a spine, which, measuring from the occipital furrow, is 

 about three-fourths as long as the glabella. Occipital furrow 

 narrow and well defined. Dorsal furrow narrow, somewhat 

 sharply defined, and continued of the same strength in front of 

 the glabella. 



