NORTH AMERICAN EARLY TERTIARY BRYOZOA. 457 



is not a good generic character, for semicircular avicularian mandibles of the 

 Porella type are observed in three genera on the following species : 



Smittina (Lepralia) concinna Busk, 1854. 



Smittina (Smittia} unispinosa Waters, 1889. 



Vmbonula (Cellepora) vrrrucosa Esper, 1791. 



Ramphostomella (Eschara) scdbra Fabricius, 1780. 



We prefer to consider the function of calcification clearly distinct on the geno- 

 types of the two genera. It is for this reason that Smittina majuscula Nordgaard, 

 1905, seems to be a Porella even though a lyrula is present. Likewise Porella gla- 

 ciata Waters, 1900, Porella laevis Fleming. 1828, and Porella piano, Hincks are true 

 Smittina on account of their frontal with pleurocyst, in spite of the presence of 

 semicircular mandibles and the absence of lyrula. 



Certain Smittina are ornamented with false tremopores, but in the interior 

 areolar pores alone are visible. 



Historical. Hincks did not indicate a genotype. The first species described 

 in his work is Smittia landsborovi Johnson, 1847, but unfortunately this is a quite 

 variable species, very difficult to determine and whose synonymy is not yet exactly 

 fixed. We prefer to adopt the second species Smittia reticulata MacGillivray 

 which has been found fossil in the Miocene. 



In 1903, Norman changed the name of Smittia to Smittina because the former 

 was preoccupied in the Diptera. In 1909, Levinsen extended the meaning of the 

 genus Smittina to inacceptable limits. Under the same name he has combined 

 two absolutely different genera. 



With Waters we can accept Norman's term but in the exact sense fixed by 

 Hincks, for Smittina is one of the most natural genera of the family. 



SMITTINA COLLUM, new species. 



Plate 58, figs. 11-17. 



Description. The zoarium is plurilamellar ; it incrusts shells or algae over large 

 surfaces. The zooecia are large, somewhat elongated, distinct, limited by a fur- 

 row or by a salient thread; the frontal is smooth, convex, bordered by a row of 

 triangular areolae ; it is formed of a smooth pleurocyst, placed on an olocyst per- 

 forated laterally, often separable. The peristomice is semilunar and bears a short 

 rimule-spiramen ; the peristomie visible externally is salient and bears laterally 

 an avicularium; the peristome is thin and sharp; the lyrula is much imbedded, 

 little visible, wide and flat. The ovicell is hyperstomial, placed on the distal 

 zooecia, opening largely into the peristomie. The avicularium is straight, tri- 

 angular, with pivot, the beak directed above. 



,, <hpe=0.20mm. . fZs=1.00-1.10mm. 



Measurements. Peristomice { , , , K Zooecia , 



[Zpe=0.12-0.15 mm. Us=0.50mm. 



Variations. On one zoarium the zooecia are not regularly arranged; they 

 radiate from false ancestrulae forming thus many subcolonies. This phenomenon 

 is frequent in the multilamellar zoaria. 



