746 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
DIPLOSOLEN COMPACTUM, new species. 
Plate 108, figs. 15-17. 
Description . — The zoarium incrusts stones; it emits tubular unilamellar ex- 
pansions. The tubes are distinct, cylindrical, fiat; the peristome is elliptical, 
horizontal, often closed by a finely punctate calcareous lamella. The adventitous 
Fig. 241. — Genus Biplosolen Canu, 191S. 
A-F. Diplosolcn obelia var. arctica Waters. A. Zoarium showing the adventitious tubules 
and the ovicell, X 25. B. Calcareous longitudinal section, showing the outer calcareous wall be- 
yond the zooecia, X 25. C. Transverse section, X 25. D. Calcareous section, X 25, showing the 
irregular wavy position of the zooecial tubes and also showing small internal projections. E. 
Ovicell with one oeciostome, X 12. At the upper part of the ovicell the base of a lateral branch 
is enclosed. F. The end of a zooecium and of an adventitious tubule, X 85, both with closures. 
From the ovicell of Fig. E. (A-F, after Waters, 1900.) 
tubules are primoserial. The ovicell is large, spread over a score of tubes, little 
globular, punctate; the oeciostome is small, isolated, little salient; each tube per- 
forating the ovicell is accompanied by its zooeciule. 
I Diameter of the peristome 0.10 mm. 
Measurements . — Distance between the peristomes 0.35 mm. 
I Separation of the peristomes 0.40 mm. 
This species is quite well characterized by the nearness of its peristomes and 
by its primoserial zooeciules. 
Occurrence . — Lowest Eocene (Bryozoan bed at the base of the Aquia forma- 
tion). Upper Marlboro, Maryland (rare). 
Holotype. — Cat. No. 65240, U.S.N.M. 
