NORTH AMERICAN EARLY TERTIARY BRYOZOA. 799 



HORNERA RETERAMAE, new species. 



Plate 144, figs. 1-S. 



Description. The zoarium is large, with reticulated branches, the fenestrae 

 of which are elongated and fusiform. The tubes are invisible exteriorly ; they bear 

 two vacuoles adjacent to the peristome and a single sulcus of little depth. The 

 peristome is little salient and orbicular. The dorsal bears longitudinal sulci of 

 little depth and very large vacuoles; the nervi are wide. 



Diameter of the peristome 0.12 mm. 



Diameter of the aperture 0.08 mm. 



Distance between the peristomes 0.50 mm. 



Separation of the peristomes 0.40-0.50 mm. 



Affinities. This species is quite constant on the whole, and we have observed 

 only the habitual alterations due to fossilization. It differs from Hornera rete- 

 poracea Milne-Edwards, 1838, in the special arrangement of the zoarial network 

 deprived of trabeculae and in which the branches are all of the same size. 



It differs from Hornera polyporoides in the absence of trabeculae and in the 

 larger, zooecial dimensions. 



Occurrence. Middle Jacksonian (Castle Hayne limestone) : Wilmington, 

 North Carolina (rare). 



Cotypes.Cat. No. 65328, U.S.N.M. 



HORNERA POLYPOROIDES, new species. 



Plate 144, figs. 9-13. 



Description. The zoarium is reticulate and formed of compressed branches 

 joined by short and thin transverse trabeculae. The tubes are invisible exteriorly: 

 they bear a single wide longitudinal sulcus, at the base of which are three, four, 

 or five large vacuoles. The peristome is wide, little salient, orbicular. On the 

 dorsal the nervi are narrow, the sulci wide and deep, and the vacuoles large. 



Diameter of the peristome 0.10 mm. 



Diameter of the aperture 0.06 mm. 



Distance between the peristomes 0.38-0.40 mm. 



Variations. The number of frontal vacuoles is quite variable according to 

 the form of the branches. The dorsal vacuoles are often smaller when the sulci 

 are more numerous (fig. 12). 



Affinities. In its zoarium, this species resembles Hornera rcteporacea Milne- 

 Edwards, 1838, but the American species differs in its more numerous frontal 

 vacuoles, in its smaller dorsal vacuoles, and in the absence of two large triangular 

 vacuoles adjacent to the peristome. 



It differs from Horm ra nteramae in its zoarium formed of branches joined 

 by narrow trabeculae and in the very great irregularity of the fenestrae. 



Occurrence. Lower Jacksonian (Moodys marl) : Jackson, Mississippi 

 (common). 



Measurements. 



