208 The American Gevlogist. April, 1902, 
Homotrypa frondosa® (Edwards & Haime) 
Pi. X, Fics. 11, 12; Pu. XI, Fics. 2, 5; Pu. XII, Fic. 1. 
Zoarium frondescent, wavy, 4 to 6 mm. thick and 30 to 50 mm, or 
more in width. The surface is studded with large rounded stellate mon- 
ticules which are sometimes slightly elongated in the axial direction 
of the frond. Monticules usually well elevated, never conical, some- 
what spreading at the base. On an average, nine occupy a space of 
one square centimeter. They are 2 mm, to 2.5 mm.* in diameter, and 
occupied by cells larger than the average. Ordinary cells very uniform 
in size, 0.2 mm, in diameter; the diameter of the large cells in the 
monticules is frequently as much as one-third mm. Fifty cells of the 
ordinary size may be counted in one cm. An occasional mesopore may 
be detected at the angles of the zocecia. 
The internal structure of this species is that of a typical Homotrypa 
(cf. H. curvata). In tangential sections, taken near the surface, the 
cells are thick-walled, with distinct true walls, and copious deposit 
of schlerenchyma. The large cells of the monticules are a conspicuous 
feature of such sections. Only an occasional acanthopore can be de- 
tected. 
Longitudinal sections show that the zocecial walls in the axial re- 
gion are thin, slightly wavy, and that diaphragms are here lacking. 
In the mature region the walls become greatly thickened, the true 
walls being seen as a double dark median line. A series of overlap- 
ping cystiphragms is present in practically every tube, and horizontal 
diaphragms in moderate number cross from the backs of the cysti- 
phragms to the opposite wall. The cystiphragms are usually on the 
concave but are occasionally on the convex side of the wall. In fig. 
12, Pl. X, a very large zocecium is shown at a and a splitting of the 
interzocecial wall at b, which may very well produce on the surface 
the effect of lines radiating 1rom the apices of the monticules, causing 
them to appear stellate.t 
The correspondence between this species and Edwards and 
Haime’s figures and description of their Chaetetes frondosus is 
remarkably close. The spacing and diameter of the monticules 
and their expression is the same. The diameter of the cells 
both small and large is the same. The monticules in both are 
distinctly stellate owing to the peculiarity mentioned above. 
Both have the same sort of thin wavy frond. 
* MR. J. M. Nickvurs, of Cincinnati, has recently described (Jour. Cin Soc. 
Nat. Hist., vol. xx, No. 2, Jan. 10, 1902, pp. 103-105) a species of Homotrypa 
(H. Bassleri) from the same hozizon as H. frondosa, which future investigation 
may prove to be connected with the latter. H. bassleri has fewer diaphragms 
and more acanthopores than H, frondosa and a much more delicate zoarium, 
+ EDWARDS AND HAIME Say 1.5 mm.; though they do not so figure them. 
In their figures the monticules have a diameter of from 2 to 3 mm. 
t See EDWARDS AND HAIMe’s figure of an enlargement of the surface of their 
species, 
