132 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.61. 



tubes. However, the direct ramifications are visible at the exterior 

 through an orifice which is a little larger, surrounded by a vei^ 

 short peristome; the secondary ramifications constitute the other 

 visible orifices. This character is quite clear in our figure. 



In transverse section the tubes are all equal, polygonal, and sur- 

 rounded by a thick lamellar tissue. 



Aflnities. — The peristomes are often more or less grouped in trans- 

 verse interrupted rows, but they never form fascicles. On certain 

 portions of the zoarium they are even arranged in quincunx, and we 

 have been able to measure their separation. 



The specimens from Meudon mentioned by D'Orbigny appear to 

 form a distinct species, Reteporidea subrainosa^ in which the peris- 

 tomes are always arranged in quincunx and the branches are more 

 divergent. 



On the posterior face (interior) there are true sulci (characteris- 

 tic of lamellar tissue ) , at the base of which are the openings of 

 the vacuoles. 



Occurrence. — Cretaceous (Maastrichtian) : Royan and Bougniaux 

 (Charente inferieure) and Ste. Colombe (Manche) (D'Orbigny) ; 

 Courgeac, Poulipiac (LeGabriel) and Manie Eoux (Dordogne), 

 France. 



Plesiotypes.—Csinu collection and Cat. No. CS972, U.S.N.M. 



RETEPORIDEA COLLARDETI, new species. 



Plate 22, figs. 10-15. 

 Descriptioii. — The zoarium is reticulate, with wide meshes, in 

 which the fenestrae are always wider than the branches. The 

 branches are thin, orbicular. The tubes are arranged in transverse, 

 irregular and interrupted rows; the peristome is thin and salient. 

 The mesopores are numerous, hexagonal, funnel shaped. On the 

 dorsal the vacuoles are small and arranged at the base of the 

 very fine longitudinal sulci. The ovicell is enormous, globular 

 salient, elliptical; it occupies the entire width of the branch; it is 

 perforated by peristomes much separated and occasionally closed. 



! Diameter of peristome 0.12 mm . 

 Diameter of branches . 80 mm. 

 Dimensions of fenestrae 2. 00 by 0.90 mm. 



Affinities. — D'Orbigny has confused this species with his lie- 

 teporidea royana; the two species are, in fact, quite similar in their 

 aspect and in their micrometric measurements. The present species 

 differs solely in its zoarial aspect with wide meshes, the fenestrae 

 being always wider than the branches. 



This species is dedicated to General Louis Collardet, military at- 

 tache to the French Embassy in Washington, District of Columbia, 



