CORALS AND BRYOZOA. 19 



Trematopora (Orthopora) parallela. 



PLATE XI, FIGS. 13, U ; AND PLATE XXIII, FIGS. 7, 8. 



Trematopora parallela. Hall. Thirty-second Kept. N. Y. State Mus. Nat. Hist., p. 1,52. 1879. 



■' " " Report of State Geologist for 1882. Expl. pi. 11, tigs. 13, 14. 18S3. 



Zoarium ramose, solid ; bifurcations infrequent ; diameter of branches 1 mm. 

 Cells tubular, arising from the center of the branch, gradually curving to the 

 surface. Apertures oval, length .20 mm., width from .12 to .15 mm. : mar- 

 gins equally elevated ; arranged in quincunx, forming longitudinal parallel 

 rows. Each aperture has some portion of its margin nearly or quite in 

 contact with four other apertures, the margins thus forming a continuous 

 elevation, which, especially when thickened by silicification, resembles a ridge 

 separating the rows of apertures. At each point of contact there is a small 

 spine. 



This species closely resembles some forms of T. regularis, but the peculiar 

 arrangement of apertures will be sufficient to distinguish it. 



Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 



DIAMESOPORA, Hall. 1852. 



Zoarium ramose, hollow, inner surface consisting of an epitheca. Intercellular 

 space solid. 



These forms differ from Trematella in having hollow branches. 



DiAMESOPORA C0N8TRICTA. 

 PLATE X, FIGS. 14-19 ; AKD PLATE XXIII A, FIG. 7. 



7Vema<oporo coruitricta. Hall. Twenty-sixth Rept. N. T. State Mus. Nat. Hist., p. 104. 1874. 

 Traaatoporaf " " Thirty-second Rept. N. Y. State Mus. Nat. Hist. p. 150. 1879. 



Report of SUte Geologist for 1882. Expl. pi. 10, Ugs. 14-19. 1883. 



Zoarium ramose ; branches frequent, hollow ; diameter from 2 to 4 mm. Thick- 

 ness of the bryozoum .33 mm. ; inner surface covered by an epitheca; marked 

 by strong concentric undulations of growth and fine striations ; fine longi- 



