206 SYSTEMATIC PALEOXTOLOGY 



spaces, wliicli are solid and concave normally, are pitted in worn speci- 

 mens as though the}^ contained covered mesopores or vesicles. The un- 

 worn covering is minutely punctate, as are also the covers closing some 

 of the zooecial apertures. The zooecia form mere inflations of the sur- 

 face, usually (perhaps always) over one of the maculae, which in that 

 case is slightly raised instead of depressed and pierced by somewhat 

 scattered apertures. An average of nine zooecia occur in 2 mm. Tube 

 walls as seen in fractured specimens, thin beneath the outer crust, min- 

 utely perforated, the pores arranged in transverse series with nearly 

 three of the rows in the space ec[ualling the width of a tube. No 

 diaphragms were observed. Length of tubes, 1 mm. or less. 



The Lower Eocene specimens have been identified with a common 

 form in the washings of the Upper Cretaceous at Yincentown, N. J. In 

 the latter the arrangement of the zooecia is usually more regular and 

 the maculae scarcely so noticeable as they are in the Upper Marlboro 

 specimens, but other Vincentown specimens agree very closely with the 

 one illustrated on Plate LIX, Fig. 3. The generic position of the species 

 may be considered a trifle doubtful. The wholly parasitic specimens 

 would probably be placed by most authors under Bereiiicea, but it does 

 not seem that the species in any of its forms is ever truly a Berenicea. 

 Besides, these parasitic specimens cannot possibly be distinguished in 

 other respects from the free laminar and even discoid specimens here 

 united with them. Discosparsa as established by d'Orbigny and ac- 

 cepted by Pergens, includes discoid or cupulif orm zoaria, attached by 

 the central portion of the base only. The zooecial apertures are dis- 

 posed irregularly or in intersecting curved lines about the center of the 

 upper surface. As these conditions are fully complied with by at least 

 some of the Vincentown specimens of D. varians, it appears reasonable 

 to place the species under Discosparsa rather than Berenicea. There is 

 no described American species closely resembling D. varians and none 

 of those from European deposits seem near enough to require detailed 

 comparison. The species is common in the Upper Cretaceous at Vincen- 

 town, N. J. 



Occurrence. — Aqtjia Foemation. Upper Marlboro. 



Collection. — Maryland Geological Survey. 



