282 PALAEONTOLOGY OF NEW YORK. 



Surface marked by comparatively strong animlations, concentric and fine 

 longitudinal Htrisa. 



This form, in being parasitic, procumbent and increasing by gemmation, 

 resembles the genus Aulopora, but the budding is always lateral, the young 

 cells, for some distance, are in contact and frequently coalescing, with the 

 parent cell ; the gemmation is more irregular and occurs nearer the base. 



Formation and locality. Hamilton group, Cazenovia, Madison county, N. Y. 



BOTRYLLOPORA, Nicholson. 1874. 



BOTRYLLOPORA SOCIALIS. 



TLATK LXIV, FIGS. 3, 4. 



BiitrylUrptnxi socicUU, Nicholsoh. Geological Magazine. Aj)ril, 1S74. 



" " " Pal. Piovime of Ontario, Canada. 1874. 



Hali,. Report of State Geologist fur 1883, p. 01. 1884. 



ZoARiDM consisting of small discoid bodies, occurring singly or in groups, con- 

 nected by vesicular tissue, adherent to foreign bodies by their under surface 

 which consists of a concentrically wrinkled epitheca : nearly all the specimens 

 observed are parasitic on Cyathophylloid or Favositoid corals, sometimes occur- 

 ring in groups of from seventy-five to a hundred zoaria ; each one having a diam- 

 eter of from 3.50 to 4 mm., convex, with a concave central area, which is some- 

 what variable in size, but usually from 1 to 1.50 mm. in diameter. Cells 

 tubular, rectangular to the surface, disposed in double radiating rows, extend- 

 ing above the surface and forming prominent ridges about .30 mm. in width; 

 a<ljacent ridges generally separated by a space about equal in width to that 

 of a ray, but sometimes more closely disposed. Alternate ridges extend 

 from the margin to the depressed central area, the others from one-half to 

 two-thirds that distance. Cell apertures minute, circular, diameter .10 or .12 

 mm., in contact, often inosculating, having the appearance of being immersed. 

 Each zoarium has from twenty to twenty-four rays, or from forty to forty- 

 eight ranges of cells. Intercellular space vesiculose, vesicles comparatively 

 large, and irregularly disposed. 



