NORTH AMERICAN EARIA" TERTIARY BRYOZOA. 417 



the cavities observed on the exterior do not perforate it; they limit the zooecia 

 between which they are hollowed out. The large frontal pores open into the same 

 zooecia (fig. 4) ; the tremopores are tubules: finally the aviculariiun is a very large 

 chamber hollowed in the thickness of the frontal wall. 



The tangential section (fig. 5) reveals the remarkable size of the avicularium, 

 a size which must correspond to a powerful musculature; the frontal is a tremocyst 

 with large pores in the form of tubules; the olocyst which surround the large frontal 

 pores show small vacuoles. 



Affiniti, .v. This is the American representative of Didynwsclla.liioculata Waters 

 of the Priabonian. It differs from this European species in its frontal which is a 

 tremocyst and not garnished with lateral areolae. 



It differs from DidymoscUa (Porina) lar-vali-s MacGillivray, 1868, in its much 

 more numerous tremopores and in its two pores placed lower. 



" In recent specimens there is usually a thick epitheca (ectocyst) covering the 

 front of the zooecia, but not closing the peristomial pores. It may possibly be a 

 Hiantopora." ( MacGillivray. ) 



Occurrence. Vicksburgian (Marianna limestone): West bank of Conecuh 

 River, Escambia County, Alabama (common) ; Murder Creek, east of Castlebnry, 

 Conecuh County, Alabama (common) ; near Claiborne, Monroe County. Alabama 

 (rare) ; 1 mile north of Monroeville, Alabama (rare) ; deep well, Escambia County, 

 Alabama (very rare). 



Gotypes.C&t. No. 62592, U.S.N.M. 



TRYPEMATELLA, new genus. 



Trypemos, in allusion to the numerous perforations of the zoarium. 



The ovicell is hyperstomial and closed by the operculum for the passage of 

 the eggs. The apertura is semilunar. with proximal border a little concave. The 

 frontal bears some lateral areolar pores (pleurocyst on olocyst). Two large lateral 

 avicularia are placed below the apertura. 



Genotype. Trypematella papulifera, new species. Pleistocene of California. 

 The type of this genus will be described in a forthcoming publication. 



Group 4, MICROPORELLAE. 



The orifice of the compensatrix (ascopore) is distinct and at some distance 

 from the apertura. The ovicell is hyperstomial and closed by the operculum. 



The presence of a frontal micropore was considered by Hincks in 1880 as an 

 important family character, but the comparison of the larvae do.es not bear out 

 this conclusion. 



According to Jullien the. ascopore, is the orifice of a horn-shaped process allow- 

 ing the exterior to communicate with the tentacular sheath. Planner and Levinsen 

 believed that this was an optical illusion, and that the ascopore Is really the orifice 

 of the compensatrix. 



5589919 Bull. 106 27 



