412 * JSYSTEMATIO PALEONTOLOGY 



are satisfied that the latter is not strictly identical with any. Keuss' 

 M. subtilimargo, as figured, also shows resemblances, but as that species 

 has been compared by competent observers with M. lacroixii, to which 

 M. bifoliata certainly is not related, we have no doubt of its specific 

 distinction. 



Occurrence. — Choptank Formation. Jones Wharf. 



Collection. — Maryland Geological Survey. 



Membranipora nitidula n. sp. 

 Plate CXTI, Fig. 1. 



Description. — Zoarium apparently erect, bifoliate. Zooecia oblong, 

 subquadrate, the length twice the width, arranged rather regularly in 

 longitudinal and diagonally intersecting series, rarely four, usually five 

 in three mm. lengthwise, about seven diagonally, and ten or eleven trans- 

 versely in the same space. Opesia elongate-elliptical, separated trans- 

 versely by an obtusely ridge-shaped wall generally equalling about half 

 their width; longitudinal interspaces about twice as great as the trans- 

 verse, medially ridged with a crescentic ovicellar excavation below 

 (i. e. in front of each opesium) and usually a small pore-like depression 

 at each end of the ridge. Very minute spines or granules on inner slope 

 of walls. 



This species resembles several of d'Orbigny's Cretaceous Biflustras, 

 especially B. prolifica, which Canu, in his revision of d'Orbigny's 

 Chilostomata, unites, together with several other forms that also look 

 very different in d'Orbigny's figures, with M. (Biflustra) lachrymopora 

 (d'Orb.). In this case, at least, we believe Canu has gone too far in his 

 zealous endeavor to reduce the Cretaceous bryozoa to reasonable specific 

 limits for we can neither believe that any species can exhibit the degree 

 of variability indicated by him for M. lachrymopora nor that d'Orbigny's 

 illustrations are so utterly unreliable. As figured by Canu, M. lachry- 

 mopora differs decidedly in the character of its longitudinal interspaces 

 from M. nitidula, and as we have found no other that matches the Mary- 

 land species any better, we have been obliged to propose the above new 

 name for it. 



Occurrence. — Choptank Formation. PaAvpaw Point. 



Collection. — Maryland Geological Survey. 



