m 



166 



rows; ridges more prominent and straight than in the 

 preceding. 



Found in the "Hamilton group, West Hamburg, Erie 

 County. X. V." (Hall, explanation of plates. ) 



Rhombopora [MMErsa. Hall. (Fig. 57.) (Pal. X. Y.. 

 Vol. VI.. p. is.!. PI. LVI.) 



Distinguishing Characters. — < )val. alternat- 

 ing apertures, disposed in longitudinal rows; 

 obsolete peristomes; prominent longitudinal 

 f it* ridges, slightly narrower than cell apertures; 

 i •■„. 57. Rhombo- comparatively prominent node, and shallow 



i.ihii ,1,1,11, is, I . X ., / v ,. ■■ 



ia (after Mali and pit at base of each aperture. 



Found in the " Hamilton group, West Ham- 

 burg, ErieCounty, X. V." (Hall, explanation of plates.) 



Genus ACAXTHOCLEMA. Hall. 



( Kiv. : Acantha, spine: klema, twig.] 

 (1887: Pal. X. Y., Vol. VI.. p. 72.) 



Bryozoum consisting of slender branches, with cylindrical 

 cells arising from a filiform axis at the center of the branch. 

 The oval cell apertures are in longitudinal or diagonally 

 intersecting rows, with ridges between. Xodes or spines 

 commonly occur. When hollow spines occur between the 

 apertures, the space below is occupied by tubuli. 



ACANTHOCLEMA SCUTULATUM. Hall. (Fig. 58.) (Pal.X.Y.. 



Vol. VI.. p. 190, Pis. LY.. LVI.) 



Distinguishing ( 'haracters. — Ridges unite 

 between cell apertures; vestibular area 

 rhomboided; at intersections of ridges are 

 prominent conical hollow nodes: when 

 worn or macerated, a crescentic opening 

 appears at baseofeach aperture; branches 

 :/^J""i.>;;:/;;;;; diverging at angle of sixty to ninety de- 



of tin- natural size; en- ■• i r-/-. 



,,.-nt of a perfect grees; diameter about . <0 mm. 



upecimen.and of a slight- f , , . . IT .. »» T 



If macerated si imen, round 111 the "Hamilton gTOUp, W est 



showing nodes and pits 



between the apertures Hamburg, Erie County. X. I. (Hall.CX- 



(after Hall and Simp & 



planation of plates. ) 





