88 PALAEONTOLOGY OF NEW YORK. 



Obs> The genus Dicranogmus was established by Corda {he. cit.) for 



a form of Lichas, in which the longitudinal furrows of the glabella become 

 obsolete before reaching the anterior margin. It is stated by Barrande (Syst. 

 Sil. du centre de la Boheme, vol. i, pp. 43, 609), that the group was founded 

 upon a single very fragmentary specimen, and it has not been accorded recog- 

 nition by him for the reason that " le prolongement plus ou moins grand des 

 sillons de la glabelle esl un caractere tres-variable dans divers types" (p. 609). 

 It is nevertheless true that very few species of the genus Lichas bear longitu- 

 dinal furrows which become anteriorly obsolete at so great a distance from the 

 frontal margin as in the species L. pustulates, Corda, which served as the type 

 of Dicranogmus ; and it may be questioned whether in any species of Lichas, 

 except those following the type of Dicranogmus, the anterior longitudinal 

 furrows become obsolete before reaching the margin. No evidence of this fact 

 is shown in the species described by Barrande, Angelin, Dames and Schmidt, 

 and none is found in any other American species of Lichas. The species Lichas 

 gibbus, Angelin, Lichas simplex, Barrande ( = Dicranogmus pustulates, Corda), and 

 IJrhas ptijonurus have in common the characteristic obsolescence of the anterior 

 longitudinal furrows and serve to form a distinct subdivision of the genus. 



Distribution. Niagara group. Coralline limestone : Schoharie, Schoharie 

 county. 



