﻿152 Proceedings of the Royal Physical Society. 



much more comprehensive, but its sole object is to indicate 

 the exact signification of the generic name here employed, 

 and the authorities followed. This explicitness is all the 

 more necessary, for the reason that Stenopora is, on the one 

 hand, represented in the collection by a large number of 

 specimens belonging to species that I consider to be new, 

 whilst, on the other hand, fossils from Spitsbergen, Nowaja 

 Semlja, and i^'orthern Eussia have been described under 

 that name ; and, as will be shown below, it is possible that 

 the latter belong, in part, to other members of the family 

 Batostomellidse. 



Stenopora hrucei, n. sp. 

 (Plate yill. Figs. 1, 2, 3, 4, and 5.) 



Zoarium ramose and dichotomous ; branches cylindrical, 

 never compressed, of an average diameter of 10 mm. The 

 largest specimen observed must have exceeded 10 cm. in 

 height, with a maximum diameter of 12 mm. The decrease 

 in the size of the diameter towards the apex is small, but 

 somewhat variable, some branches tapering more rapidly 

 than others. The base of attachment has not been met with, 

 but nothing has been observed that would lead one to 

 suspect that the dichotomous stems are offshoots of more 

 massive zoaria. Surface even, showing neither monticules 

 nor maculee. Zoaecial apertures subcircular, separated by 

 very thin interspaces — about three apertures can be counted 

 within the space of 1 mm. JsTearly every junction angle 

 between the apertures shows the blunt projection of an 

 acanthopore. On longitudinal fractures the zo^cial tubes 

 are seen to proceed in a gentle curve to the surface, to which 

 they are perpendicular for a distance of a little over IJ mm. 

 About thirty of these may be counted within 1 cm. With 

 the aid of a low-power lens, or even with the unaided eye, 

 one can easily observe in the peripheral region the periodical 

 constrictions of the casts of the tubes corresponding to the 

 moniliform swellings of the walls. 



Microscopical Examination. — Tlie walls of the zosecia are 



