ART. 14 FOSSIL AND RECENT BRYOZGA CANU AND BASSLER 63 



irregularity of the proximal portion of the opesium indicates that the 

 retractor muscles of the polypide are not attached to the zooecial 

 median axis. The ectocyst is Hght colored when it is not pink, very 

 thin, and almost transparent. 



Biology. — The colony expands often over large surfaces and one of 

 our specimens measured 4 by 2 centimeters. It becomes pigmented 

 easily. Smitt cited the cryptocyst as being of a marine-bluish hue; 

 one of our specimens was rose and green and covered by a flesh-colored 

 ectocyst. 



We have observed colonies developed on the two sides of a dead 

 shell. This is a phenomenon that is not rare, but the explanation of 

 it is difficult. It is necessary to admit either an accidental turning 

 of the shell or its vertical position between two stones which serve to 

 support it. This is almost a littoral species. 



Occurrence. — Tortugas, Florida, 16 meters (Smitt); Punta Rosa, 

 Florida. 



Plesiotype. —C&t. No. 7513, U.S.N.M. 



HEMISEPTELLA HEXAGONALIS, new species 



Plate 28, Figure 9 



Description. — The zoarium is incrusting. The zooecia are distinct, 

 separated by a very thin and shallow furrow, hexagonal, somewhat 

 elongated; the mural rim is thin and finely granulated; the cryptocyst 

 is concave, little developed, much smaller than the opesium, granu- 

 lated. The opesium' is large, elongated, dissymetric in its proximal 

 portion, often sub trifoliate; it is bordered by short and widely spaced 

 spicules. In all the interzooecial angles there is a large smooth and 

 hollow tubercle. 



-,, s r\ ■ {Jio = O.SOmm.. 



Measurements. — Opesmm -^7 .„. 



^ lZo = 0.24mm. 



fig = 0.45 mm. 



Zooecium ,, ^ ^_ 



Us = 0.35mm. 



Affinities. — The micrometric dimensions are quite variable; of the 

 primoserial, adjacent zooecia, there is one of them always shorter. 

 The initial zooecium of a series is frequently broader. The crypto- 

 cyst is little developed on the marginal zooecia. 



This species differs from Hemiseptella (Biflustra) denticulata Smitt, 

 1873, in its granulated and m.uch smaller cryptocyst. It differs from 

 Memhranipora denticulata Busk, 1856, of Mazatlan in the presence of 

 large tubercles and in its hexagonal zooecia. It differs from Hemi- 

 septella tuberosa Canu and Bassler, 1923, from the Pleistocene of 

 South Carolina in its much larger dimensions. The very special form 

 of the opesium does not permit us to compare this species with Nit- 

 scJieina {Memhranipora) of the memhranacea group. 



