NORTH AMERICAN EARLY TERTIARY BRYOZOA. 217 



DIPLOPHOLEOS SAGITTELLARIUM, new species. 



1'hite 34, figs. 5-7. 



Description. The zoariuin incrusts shells and bryozoa. The zooecia are hex- 

 agonal, indistinct, with their mural rims confluent; the cryptocyst is shallow, 

 oblique toward the opesium, very finely granulated, longer than the opesium; the 

 polypidian convexity projects but little, occurs below the opesial denticles, and is 

 elevated almost vertically ; the opesiular openings are large, round ; the opesium 

 is transverse in appearance (with the opesial openings), semilunar, narrowed ante- 

 riorly by two lateral teeth above the opesiules. The ovicell is an inconspicuous 

 distal convexity. The onychocellarium is straight, much larger than the zooecium, 

 with the form of a small leaf of the plant Sagittaria, terminated by a large mandi- 

 bular area; its opesium is oval, the point at the top, entire or crenulated. Dimor- 

 phism is manifested by large and small zooecia. 



Measurements. Opesium of small !, 



. J . . ,. /?=O.OSmm. 

 zooecium (a) including 7 Alri n ^ n 



. . 5 |Z0=0.1G-0.12mm. 



opesiules 



, iLs=OAOmm 

 bmall zooecium (a) , 



1/0=0.34 mm. 



Opesium of large , 



/r>\ i v Ao=0.16mm. 

 zooecium (B) including , _ 



- fo=0.10-0.12 mm. 

 opesiules 



, , fZs=0.50mm. 

 Large zooecium (/>) , .. 



lfe=0.34mm. 



Opesium of jA<m=0.20mm. 

 onychocellarium [Iopn=0.l2 mm. 



fLon=0.70 mm. 

 Onvchocellanum \ 7 



(7.on=0.30 mm. 



Variations. The large zooecia occur less frequently. Well preserved speci- 

 mens have the aspect of Stec/anoporeTla; but if the specimen is turned and the 

 interior is examined, the internal divisions characteristic of Steganoporella. limit- 

 ing the polypidan tube, can not be seen (fig. 7). 



Good specimens also show that the polypidian convexity is elevated almost 

 vertically as in Thalamoporella. and when the opesial denticles are united with the 

 convexity, such examples have then a constitution identical with that of this genus. 

 The ovicells however are very different (fig. 5). 



Most often the polypidian convexity is broken or not developed, but the 

 opesiular openings are always quite distinct (fig. 5). 



The zooecial dimorphism has to do perhaps with a double system of nutrition. 



Affinities. Its zooecial dimorphism and the form of its onychocellarium clearly 

 characterize this beautiful species. It differs from DipJopkoleos sagittarium in 

 the smaller dimensions of its onychocellarium and in the absence of opesial denticles 

 in this organ.' 



