746 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



DIPLOSOLEN COMPACTUM, new species. 



Plate 103, figs. 15-17. 



Description. The zoarium incrusts stones; it emits tubular unilamellar ex- 

 pansions. The tubes are distinct, cylindrical, flat; the peristome is elliptical. 

 horizontal, often closed by a finely punctate calcareous lamella. The adventitous 



F 8S 



FIG. 241. Genus Diplosolcn Canu, 1918. 



A-F. Diplosolcn obi'lia vnr. 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 zooeeial tubes and also showing small internal projections. E. 

 Ovicell with one oeciostonie, 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. 



Diameter of the peristome 0.10 mm. 



Measurements. Distance between the peristomes 0.35 mm. 



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.C&i. No. 65240, U.S.N.M. 



