288 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



,, JAa=0.10mm. . f 7,3 = 0.60 mm. 



Measurements. Aperture i , . , Zooecia {, 



I ?=0.15 mm. I Zs=0.35 mm. 



Affinities. The development of the oral mucro is remarkable; it is well illus- 

 trated in figure 12. The two nearly vertical arches situated under the two bifur- 

 cations of the mucro circumscribe two large pores (or eyes), which may be dis- 

 tinguished clearly from the underlying radial lumen on the cribriform area. In 

 the Cretaceous there are other spinose growths still more remarkable, as in the genus 

 Steginopora D'Orbigny. 1852. 



The secondary orifice, which results from this development of the oral mucro, 

 is smaller and more irregular than the primary one or apertura, which is only 

 slightly visible. 



The oral spines are rarely seen ; when they exist, they are four in number and 

 are never borne by zooecia with avicularia. 



This species differs from Membraniporella ulrichi in its incrusting zoarium, 

 its very convex cribriform area, its smaller oral avicularia (Lv 0.20 mm. and not 

 0.25 mm.), and in its smaller ovicell. 



We have seen only three specimens of this remarkable species, so we are unable 

 to make a more detailed study. 



Occurrence. Middle Jacksonian: near Lenuds Ferry, South Carolina (rare). 



Cotypes.C&t. No. 64021, U.S.N.M. 



MEMBRANIPORELLA COMPRESSA, new species. 



Plate 41, fig. 6-S. 



Description. The zoarium is free, cylindrical, or compressed. The zooecia 

 are distinct, elongated, elliptical, separated by a furrow, and surrounded by a 

 more or less developed gymnocyst. The .frontal is quite convex ; the costules are 

 delicate without lumen pores, largely separated by a Ions' initial slit following two 

 lacunae. The ovicell is unknown. The aperture is transverse, semi-elliptical, and 

 provided with a slightly salient and very thin border. 



T., (haOWmm. . [Zs=0.50mm. 



Measures. Aperture {, 1 Zooecia' 



l?<z=0.12mm. [fe=0.30mm. 



Affinities. Norman l has shown that in the variety intermedia of Membrnni- 

 porella nitida, the type of the genus : " the radiating ribs coalesce with each other by 

 crossbars so as to form roundish openings, lateral lacunes;" and that, "in fact, 

 this Madeiran form in its structure is in all respects a true Cribrilina." 



We have noted also that Membraniporella subagassizi with reference to the 

 separating slits of the zooecia may or may not have such lacunae. 



Here the lacunae are constant. But we can not classify the species in Cribrilina 

 because of the initial slit and the absence of lumen pores, nor in Puellina 

 because of the great size of the lacunae and of the initial slit. Provisionally at 

 least, the species may be retained in Membraniporella Smitt. 



1 1909. Norman On the Polyzoa of Madeira and neigbborins islands. Journal Linnean Society, vol. 31. 

 p. 288, pi. 36, fig. 7. 



