ART. 22. CYCLOSTOMATOUS BRYOZOA CANU AND BASSLER. 131 



exterior aspect, for the mesopores are quite expanded at their 

 terminal extremity. 



Affinities. — The peristomes are salient and thin. The mesopores 

 are much expanded, irregularly arranged around the peristomes. On 

 the dorsal the vacuoles are also much expanded in their terminal 

 portion; they are arranged in rather regular quincunx. The trans- 

 verse rows of peristomes are not fasciculated and the peristomes ar- 

 ranged in quincunx are not rare. 



The fenestrae of the zoarium are always less wide than the 

 branches ; the species diifers from Retejwridea collardeti in this char- 

 acter. 



Occurrence. — Cretaceous (Maastrichtian) : Royan and St. Leger 

 (Charente inferieure), Ste. Colombe (Manche), (D'Orbigny), Tal- 

 mont, and Bessac, France. 



The specimens from Meudon, near Paris, noted by D'Orbigny as 

 belonging to this species appear to us on the contrary to form a 

 distinct species {R. collardeti) . 



Plesiotypes.—Canu collection and Cat. No. 68972, U.S.N.M. 



RETEPORIDEA RAMOSA D'Orbigny. 1854. 



1854. Reteporidea ramosa d'Oebigny, Paleontologie frangaise. Terrain 

 Cr6tace, vol. 5, Bryozoaires, p. 938, pi. 608, figs. 6-10 ; pi. 773, figs. 1-3. 



1889. Hornera ramosa Peegens, Revision des Br.yozoaires du Cretac6, fig- 

 ures par d'Orbigny, Memoires de la Societe Beige de Geologie, etc., 

 vol. 3, p. 353. 



1899. Hcmicellaria ramosa Geegory, Catalogue of Fossil Bryozoa in Brit- 

 ish aiuseum, Cretaceous, p. 371. 



Diameter of peristome 0.12-0.14 mm. 



Distance between peristomes .30 mm. 



Separation of peristomes .36 mm. 



Diameter of branches 1.40 mm. 



Structure. — The zoarium is not reticulated, but it offers the same 

 peculiarities as that of Reteporidea royana D'Orbigny, 1850. It is 

 large, conical ; its base is discoidal and little expanded. The cellular 

 face is exterior; the noncellular face is interior. The zoarium does 

 not therefore constitute a trap for diatoms. The walls are very thick 

 and are formed of lamellar tissue. 



In longitudinal section the tubes are cylindrical, oriented toward 

 the exterior, with gemmation by bifurcation at all heights (periphe- 

 ral). There is no basal lamella. 



The mesopores are divergent, not parallel to the recurved extremity 

 of the tubes; buried in the lamellar tissue, they are little apparent. 

 They are much widened in their terminal portion. 



The vacuoles are capillary, numerous, adjacent, and perforate 

 a very thick lamellar tissue. These are the ramifications of the dorsal 



Measurements. — 



