NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 



153 



Those of the smaller set occur in the depressed spaces, usually close beside the zooecial orifice, and 

 rarely on the reverse of the branches. 



This common species of the Choptank formation apparently belongs to the Retepora-cellulosa group 

 of Waters. Though resembUng several of the species of the group rather closely we could not decide 

 that it was any nearer to one than to another. Still, having found it difficult to make thoroughly 

 satisfactory comparisons, we will not be greatly surprised should future study prove R. doverensis to 

 belong to some previously described species. 



The peristome bears a wide, very irregular, rimule spiramen. The ovicell is 

 fissured. 



Occurrence. — Miocene (Choptank formation) : Dover Bridge and Jones Wharf, 

 Maryland (common). 



Cotypes and plesioty pes. —C&t. Nos. 68660, 68661, U.S.N.M. 



A.Retepora g. Phidolopora C.Rhynchozoon 



D.Hippellozoon 



E . Schizellozoon F. Triphyllozooii 



G Schizotheca 



H . Lepraliella 



Fig. 27. — Genera of the family Reteporidae Smitt, 1867. 



A. ReUpora beaniana King, 1846, X 25. Recent. (After Hincks, 1880.) B. PMdolopora labiala 

 Gabb and Horn, 1865, X 20. Pleistocene of California. C. Rhynchozoon angulatum Levinsen, 

 1909, X 55. Recent. (After Levinsen, 1909.) D. Hippdlozoon novaczelandiae Waters, 1894, X 25, 

 Recent. (After Waters, 1894.) E. Schizellozoon impcrati Busk, 1884, X 25. Recent. (After Waters, 

 1885.) F. Triphyllozoon moniliferum MacGilli\Tay, 1860, X 85. Recent. (After Waters, 1894.) 

 G. Schizotheca fissa Busk, 1858, X 45. Recent. (After Hincks, 1880.) H. Lepraliella conligua Smitt, 

 1867. Recent. (After Levinsen, 1916.) 

 12184— 23— BulL 125 11 



