Cotze—On Hemitrypa hibernica. 141 
Judged by these combinations of characters, the Galway speci- 
mens are seen, by their positions in the tables, to be practically 
identical, and also identical with 3, one of Griffith’s and M‘Coy’s 
specimens of H. hibernica. land 2, which are important specimens, 
diverge from this group only on account of variations in the number 
of zocecia (tegminal openings) per centimetre. The agreement in 
other points is so close that I would regard the whole group 1 to 
4b. as illustrating typically H. hibernica, admitting the range in 
the number of the zocecia. 
But 5 and 6, representing the nearest American species, stand 
away from the Irish group. Prout’s statement that there are 
about two zocecia to each fenestrule may easily cover a larger 
number, and, as indicated by the arrow on tables II. and III., 
may bring his account closer to that of Ulrich ; such proximity is 
seen in table I., which is based on another pair of characters. ‘The 
American species H. proutana may, I believe, be regarded as a 
mere variety of the prior H. hibernica; but it is distinctly marked 
by a more delicate structure throughout than is the case in the 
Trish forms at present studied. The range of horizon and locality 
in the latter is good evidence that the characters above stated fairly 
represent the species H. hibernica. 
The Galway specimens are here figured (Pl. vi1t.) ; fig. 3 shows 
a very happy dissection of the zoarium, produced by fracture of a 
thin slice. The great secondary thickening on the reverse of the 
columns has been pulled away, disclosing the original delicate 
ribbing. ‘The original more transparent zocecial wall is also well 
seen in fig. 1. The thickening takes place in waved layers as if 
delicate spines were first shot out, between which the further 
calcareous deposition went on. Similarly in sections of Carinopora 
Hindei, kindly lent me by Dr. G. J. Hinde, the great keel is 
seen to be built up around a delicate and more transparent central 
lamina. 
With regard to the nature of the animal that dwelt in the 
zocecia of Hemitrypa, and yet protruded itself far enough through 
its narrowed vestibule to reach, and require a special aperture in, 
the outer tegmen, one can only point out that its habits must have 
frequently brought it into contact with the tegmen, and that its 
tentacles probably extended beyond that meshwork. Indeed, the 
tegminal openings in most Hemitrypas suggest that the mesh is 
