CLINTON GROUP. 



23 



Genus RUSOPHYCUS. 



[ Gr. purftfog, or putfoS, rugose ; and c^Mxoi, fucus, a sea-plant.] 



Character. Plant consisting of simple or branched stems, which are transversely rugose or 

 wrinkled. 



The genus includes also the bilobate forms which are not much elongated, and which may be 

 attached by stems or pedicels of different character (ex. R. bilohatus). It differs from Ar- 

 THKOPHYCUSj in being irregularly wrinkled transversely, while that is distinctly annulated. 



411. 1. RUSOPHYCUS CLAVATUS(n.*^.). 



Pl. VIII. Fig. 1 a, b. 



Plant short ; stems thick, subangular, enlarging from the root upwards ; surface transversely 

 ridged, or rugose with one or more longitudinal grooves on one side. 



This species has, in some degree, the characteristic marks of Arthrophycus in its transverse 

 rugge or articulations, but is short, thick, and scarcely flexuous. Sometimes apparently two stems 

 grow from a single root. Specimens of this form never attain a length of more than three or 

 four inches. 



Fig. 1 a. A specimen with two stems, apparently proceeding from a single root, 

 Fig. 1 b. A smaller single specimen. 



Position and locality. Blackstone's quarry, New-Hartford, Oneida county. 



412. 2. RUSOPHYCUS SUB ANGULATUS(n.*jt).), 



PL. VIII. Fig. 2 a,b. 



Stems subquadrangular, elongated, simple, transversely rugose, lor^gitudinally grooved on one 

 side. 



Fragments of this species are abundant in the shaly layers of the central part of the group : 

 they are all characterized by having a subquadrangular stem vdth a longitudinal groove, which, 

 in some specimens, gives them a bilobate appearance. It differs from the last principally in the 

 stem being of equal dimensions throughout, and usually more elongated. 



Fig. 2 a. A specimen of large size, and greater than the ordinary length. 

 Fig. 2 b. Two fragments of smaller size. 



Position and locality. Blackstone's quarry. 



