POLYPS AND CORALS. 25 



Family, Poritid^ Dana. 



PoRiTES TENUIS Yerrill, nov. sp. 



Corallum glomerate j globose, attached by a narrow 

 base ; surface irregular and uneven. Cells very small and 

 shallow, crowded, polygonal. Walls thin and very porous. 

 Septa twelve, imperfect, open trabicular. Pali five or six, 

 well developed. Columella very small, tubercular. 



Diameter of the largest specimen collected 2.5 inches ; 

 of cells .05. 



Loo Choo Islands ? Dr. Wm. Stimpson. 



PORITES sp. 



A small specimen of a glomerate species, too young for 

 specific description, is in the collection. 



The cells are polygonal, rather deep, with twelve weU 

 developed septa and six strong pali forming a circle around 

 the deep, open, central space in which there is no columella 

 visible. Walls well developed, angular, acute. 



Diameter of the cells .06. 



Hong Kong, China. Dr. Wm. Stimpson. 



The well developed walls and pali, and the absence of 

 columella cause this species to approach closely to Rhoda- 

 raa, to which it may hereafter be necessary to refer it 

 when more complete specimens are obtained. It has, how- 

 ever, but two cycles of septa instead of three found in the 

 typical species of that genus. 



^ MoNTiPORA POLiosA ? Edw. and Haime. 



A frond-like branch about seven inches high and having 

 a width near the top, where it is thin and has the sides curved 

 inward, of about four inches. The basal portion is a stout 

 stalk, convex externally and concave within, dead below, and 

 curving outwardly so that the flat part of the frond has an 

 oblique position. The upper or inner surface is densely cov- 

 ered by rather large, angular, very irregular and unequal 

 prominences, which often unite into longitudinal crests of 



COMMUNICATIONS ESSEX INST., VOL. V. 4. MAT 30, 1866. 



