BRYOZOA. 323 



Crepipora epatiosa.] 



Mesopores very few. In vertical sections the walls are thin, with faint transverse 

 lineation, and somewhat irregular. Diaphragms occur sparingly and at unequal 

 intervals in the zocecial tubes, but in the mesopores which, being few, are not often 

 seen, they are numerous. 



The absence of clusters of large cells and the greater average size of the 

 ordinary zooecia will distinguish this peculiar species from associated Bryozoa 

 having a similar mode of growth. 



Formation and locality. Rare in the upper third of the Trenton shales at St. Paul, Minnesota. 



CREPIPORA SPATIOSA, n. sp. 



(Not figured.) 



This name is proposed for a massive or heavy lamellate form that occurs in the 

 Bryozoa layers at the top of the Trenton near Harrodsburg and Frankfort, Ken- 

 tucky. It is closely related to C. hemispherica Ulrich (upper beds of Hudson River 

 group in Illinois), on the one side, and C. perampla on the other. From the first it 

 differs in the greater size and different shape of its zoarium, in having thinner walls 

 and fewer diaphragms, and less distinct lunarium. The second has larger zooacia 

 and even less developed lunarium, but in other respects is very similar to the Ken- 

 tucky species. 



Specimens of this species may attain a diameter of 300 mm. with a thickness of 

 from 50 to 100 mm. Of the ordinary zooecia twelve occur in 5 mm. Diaphragms 

 0.4 to 1.0 mm. apart. 



CREPIPORA PERAMPLA, n. sp. 



PLATE XXVIII, FIGS. 29-32. 



Three specimens have been seen of this. One, about 70 mm. in diameter and 

 33 high, is hemispheric, with the base concave and the margin flaring slightly. The 

 others are larger (about 95 mm. in diameter) and, though worn, the basal part of 

 the zoarium seems to have been convex instead of concave. Zooecia large, with very 

 thin walls, generally of angular shapes, the pentagonal and hexagonal more common 

 than the subrhomboidal; those of the average size about 0.5 mm. in diameter, with 

 nine or ten in 5 mm. At intervals of 5 or 6 mm. clusters of tubes of more or less 

 decidedly larger size than the ordinary are to be observed. Some of these may 

 attain a width of 0.9 mm., but as a rule their size varies between 0.6 and 0.8 mm. 

 Mesopores very few. 



