Cyathocormus mirabilis n. g., n. sp. 2^1 



iicial layer, and terminate quite abruptly at the level where the 

 first row of stigmata begins to appear. As already motioned, the 

 basal part of the head as well as the whole peduncle is entirely 

 composed of test substance which is somewhat firmer and a little 

 more opaque than that of the side w^alls of the head. 



The test consists of a hyaline homogeneous matrix in which 

 two kinds of cells are imbedded, the bladder cells and the test 

 cells. The former are very large, oval, spherical, ellipsoidal, or 

 polygonal in shape, and have only a thin layer of protoplasm 

 lining the inner wall, against which the nucleus lies (PI. I., fig. 5, 

 h.c). The nuclei are veiy distinct, oval or fusiform in shape, and 

 are always situated close to the inner wall of the cell. There is 

 often a little mass of protoplasm at the point where the nucleus 

 lies. The bladder cells are exceedingly numerous throughout, 

 forming by far the greater part of the test tissue. In some places 

 they are so numerous that the matrix exists only in the form of 

 delicate membranes surrounding the large vesicles which have 

 become polygonal by mutual pressure. The test cells are found 

 wherever a small patch of matrix can be seen (PL I., fig. 5, t.c). 

 They are small (0.005 — 0.006 mm. in diameter), oval or ellipsoidal 

 in shape, and consist of a large nucleus surrounded by a small 

 quantity of protoplasm. 



In the superficial layer of test forming the external covering 

 of the head the tissue consists mainly of bladder cells generally 

 arranged in a single layer with onty a little mass of matrix about 

 them (PL I., figs. 7,9,10,11). This layer, therefore, is throughout 

 its whole extent only just as thick as the greater diameter of the 

 bladder cells. The walls of test substance intervening between 

 the branchial regions of the zooids are in some places much 

 thicker than the surface layer and may contain a large number of 

 bladder cells grouped irregularly, but in other places they are 

 extremely thin and are entirely composed of matrix, being in fact 

 too thin to contain a bladder celL In the thickened masses of 

 common test enclosing the abdominal regions of the zooids the 

 bladder cells are also abundant, but small patches of matrix are 

 found here and there, and in such places the test cells are very 

 clearly visible (PL I. , fig. 5). 



