86 PALAEONTOLOGY OF NEW YORK. 



\ ive both these pairs of spines are the bases of two or three strong tubercles, 

 which were probably spiniform. The principal pair of spines was evidently 

 more divergent than the single pair in Lichas gryps. The lateral lobes are 

 almost obsolete, each hearing a spine just within the orbital node. The pos- 

 terior portion of the head-shield has not been observed. 



Distribution. Upper Helderberg group. Corniferous limestone : Schoharie, 

 Schoharie county ; Lelloy, Genesee county. 



[s.-g.] DICRANOGMUS, Corda. 1847. 

 Lichas (Dicranogmus) pttonurus, n. sp. 



PLATE XIX B, FIGS. 19-21. 



Cepiialox sub-semicircular in outline. Surface depressed-convex, flattened above 

 and sloping gently in all directions to the margin; indistinctly trilobate. 

 Border narrow, slightly thickened and produced into short spines at the 

 genal angles. 



Glabella large, sub-quadrate. Frontal lobe depressed, narrow, sub-rectan- 

 gular; its width less than one-third that of the glabella ; not differentiated 

 from the lateral lobes on the anterior third of the shield; extending to the 

 occipital furrow and constricted just behind the middle by a transverse 

 depression, which is continuous with the second pair of lateral furrows. 

 First lateral furrows longitudinal, parallel, shallow and becoming obsolete 

 on the anterior one-third of the shield; second lateral furrows strong, 

 transverse, at right angles with the first pair, and extending to the palpebral 

 furrow with a slight forward curve; third lateral furrows beginning at the 

 termination of the second pair, thence backward, parallel for a short distance 

 and merging into the occipital furrow. First lateral lobes large, indistinctly 

 defined on the antero-lateral mar-ins, and coalesced with the frontal lobe 

 anteriorly, forming a single conspicuous, semicircular subdivision, extending 

 lor more than one-half the length of the head; second lateral lobes smaller, 

 sub-quadrate, and distinctly separated from the palpebral lobes by a sulcus; 

 third lateral lobes obsolete. Occipital furrow narrow, deeply impressed 



