ART. 2] CYCLOSTOMATOUS BRYOZOA CANU AND BASSLER 77 



LEIOSOECIA GRANDIPORA, new species 



Plate 16, figs. 1-4 



Description. — The zoarium is free, cylindrical, bifurcated. The ori- 

 fices are polygonal; the peristomes are thin, nonsalient. The meso- 

 pores are large, polygonal, few in number, irregularly placed. The 

 ovicell is large, orbicular, convex, smooth. 



Measurements. — Diameter of aperture, 0.12 mm. ; diameter of meso- 

 pores, 0.10 mm.; diameter of zoarium, 4 mm. 



Structure. — In longitudinal section the tubes are cylindrical, with 

 very thick walls, recurved at their extremity, with axial gemmation. 

 The mesopores have a variable length; they appear at all heights and 

 their distinction from the tubes is very difficult; they appear little 

 numerous. 



In transverse section the tubes are polygonal, with adjacent walls, 

 as large at the center as at the periphery. The terminal thickening 

 of the tubes and of the mesopores forms a thick parietal zone. 



Affinities. — The species differs from Leiosoecia aequiporosa in its 

 apertural diameter of 0.12 mm. and in its larger zoaria. 



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

 land (rare). 



Coty pes. —Cat. No. 69932, U.S.N.M. 



LEIOSOECIA CONSTANTI D'Orbigny, 1850 



Plate 17, figs. 1-5 



1850. Ceriopora constanti D'Orbigny, Prodrome de Pal^ontologie, vol. 2, p. 143. 

 1854. Heteropora constanti D'Orbigny, Pal^ontologie frangaise, Terrain Cr6tac6, 

 vol. 5, p. 1071, pi. 799, figs. 6, 7. 



Measurements. — Diameter of orifice, 0.10 mm.; diameter of peri- 

 stome, 0.14 mm.; diameter of mesopores, 0.06 mm.; diameter of 

 terminal branches, 3 mm.; diameter of large branches, 7 mm. 



Structure. — We have found very typical specimens corresponding 

 to D'Orbigny's figures. They have, indeed, polygonal orifices sur- 

 rounded by small mesopores. Moreover, the zoarial surface presents 

 undulations and in places circular areas of mesopores. 



Other specimens, less typical in appearance, have the same aper- 

 tural diameter, the same orbicular area of mesopores, the same char- 

 acters in longitudinal section, but the zoaria lack the undulations, 

 and the mesopores (0.07, 0.08 mm.) are a little larger. 



It is difficult to recognize two species in these specimens. The 

 fu'st lot seems to us to be the terminal branches, the second, more- 

 over, larger, are the large adult branches. On the other hand, on 

 the same specimen it is easy to observe the variations in the size o^ 

 the mesopores. 



In longitudinal sections the tubes are cylindrical, with rather reg- 

 ular peripheral gemmation. The mesopores are rather long and 



