82 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.67 



REPTOCLAUSA DENTICULATA, new species 



Plaf.e 18, fig. 1 



Description. — The zoarium creeps over shells in fronds branching 

 at a right angle. The tubes are arranged on each side of the median 

 crest in transverse rows. There are two tubes in each row; the peri- 

 stomes are denticulated and nonadjacent. All the branches are sur- 

 rounded by a more or less broad foliaceous expansion formed of 

 aborted tubes. 



Measurements. — Diameter of peristomes, 0.16 mm.; maximum 

 diameter of branches, 1 mm. 



Affinities. — In its zoarial simplicity this species much resembles 

 Idmonea alipes Gregory, 1899, but differs in its denticulate peristomes. 



Occurrence. — Lower Cretaceous (Aptian) : Faringdon, England. 



Holotype.—C&t. No. 6993G, U.S.N.M. 



REPTOCLAUSA HAGENOWI Sharpe, 1854 



Plate 18, figs. 2-5 



1899. Idmonea hagenowi Gregory, Catalogue of the Cretaceous Brj^ozoa in the 

 British Museum, vol. 1, p. 152, pi. 8, fig. 1. (Bibliography.) 



Structure. — We have been able to make some sections of this spe- 

 cies. In transverse section through a fascicle the tubes are rounded, 

 and in the vicinity of the crest they are surrounded by a strong 

 solid epitheca. In longitudinal section the tubes are short, oblique, 

 club-shaped; the crest is a thickened continuous epitheca. 



On the fascicles the tubes are arranged in quincunx; the peri- 

 stomes are orbicular and somewhat salient and their diameter is 

 larger in the vicinity of the crest of the fascicles. 



Occurrence. — Lower Cretaceous: Faringdon, England (Aptian); 

 Villers-le-Lac (Doubs) , France ( Valangian) . 



Plesiotype.— Cat. No. 69937, U.S.N.M. 



REPTOCLAUSA MEANDRINA De Loriol, 1868 



Plate 18, figs. 6-8 



1868. Reptoclausa meandrina De Loriol, Valangini^n d' Arzier, Paleontologie 

 Suisse, Liv. 4, p. 62, pi. 6, fig. 1. 



The zoarium encrusts Terebratulas and oyster shells. The peri- 

 stomes are wider than in Reptoclausa hagenowi and the fascicles are 

 arranged much more irregularly. The interfascicular tubules are 

 often visible exteriorly. We have found beautiful specimens in our 

 collections. 



Occurrence. — Lower Cretaceous (Valangian) : Sainte-Croix and 

 D' Arzier, Switzerland. 



Plesiotype.—C&i. No. 69938, U.S.N.M. 



