166 



rows; ridges more ])i'oiiiinent and straight than in the 

 preceding'. 



Fonnd in the "Hamilton gron]). West Ham}»nrg, Erie 

 County, X. Y." ( Halh explanation of plates. ) 



Rhombopora immeksa. Hall. (Fig. 57.) (Pal. N. Y.. 

 Vol. YI., p. 185, PI. LYl.) 



Distinguishing Characters. — Oval, alternat- 

 ing apertures, disposed in longitudinal rows: 

 obsolete jieristomes : prominent longitudinal 

 ridges, slightly nari-owei- than cell apertures: 

 Fig. 57. Rhombo- eom])aratively prominent node, and shallow 



pora inimersa. x . . , i .. i , 



12 (after Hall and i)it at oase oi each aperture. 

 ™^^°"' Fonnd in the '•Hamilton group, West Ham- 



burg, Erie County, X. Y." (Hall, explanation of plates.) 



Gkxus ACAXTHOCLEMA. Hall. 



[Ety. : AciDitJia, spine; lienm, twig.] 

 (1887: Pill. N. Y., Vol. \\., p. T'2.) 



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 

 int€'rsecting rows, with ridges between. X'^odes or spines 

 commonly occur. \Yhen hollow spines occur between the 

 apertures, the space below is occupied by tubuli. 



AcAXTHOCLEMA scutulatum. Hall. ( Fig. 58. ) (Pal.X.Y.. 

 Yol. YI.. p. 190, Pis. LY.', LYI.) 



Distinguishing Characters. — Ridges unite 

 between cell apertures: vestibular area 

 rhomboided : at intersections of ridges are 

 j)rominent conical hollow nodes; when 

 worn or macerated, a crescentic opening- 

 appears at base of each aperture; branches 

 s^m,J""F!^!Z^ diverging at angle of sixty to ninety de- 

 rari™t"of a'p'Vrfect grccs ; diameter about .70 mm. 



specimen.andof a slight- -.^ ^ . ,, , tt •\^ if 4- 



ly macerated specimen. 1 OUUCl Ul the HamiitOll gTOUp, V\ CSt 



showing nodes and pits t^ ■ r^ ^ x- a- •' / TT n 



between the apertures Hamburg, Erie Couiitv. -N . 1. (Mail.ex- 



(after Hall and Simp- ^ 



son)- planation of plates.) 



