BRYOZOA. 451 



situated between the zooecia, projecting more or less into one 

 or the other zooecial cavity, occasionally situated at the angles. 



The affinities of this species are with A. septosa Ulrich, but 

 its thinner walls, less numerous acanthopores, and more robust 

 growth easily separate it from that form. 



Position and locality: Cincinnati group. Wilmington, 111. 



AMPLEXOPORA PVSTULOSA Ulrich. 



PL XXXVI, fig. 3-3e. 



Zoarium subrainose, lobate or irregularly compressed, of an 

 average thickness of eight mm. Surface rarely smooth, gener- 

 ally set with low monticules, about 2.6 mm. apart from center 

 to center, consisting of groups of larger cells with a few small 

 ones. Zooecial walls a little flexuous, thickened somewhat in the 

 cortical region. Zooecia polygonal, hexagonal and pentagonal, 

 about nine in two mm. Apertures subpolygonal, those in the 

 monticules one-half larger than the others. In the axial region 

 the diaphragms are about twice their diameter apart, but 

 become more numerous as the peripheral region is reached, 

 where they are somewhat less than a tube diameter apart. 

 Aeauthopores fairly numerous, commonly situated at the angles. 

 Usually there are two or three superposed mature regions with 

 diaphragms very crowded where the transition from one to the 

 next takes place. 



This species differs in several important respects from A. sep- 

 tosfi Ulr. In that species acanthopores are more numerous and 

 project into the visceral cavity, tubercles are wanting or but 

 slightly elevated and the growth is strictly ramose. 



Position and locality: Cincinnati group. Hanover. Clarks- 

 ville, and other localities in Ohio; probably occurs at Wilming- 

 ton, 111. 



MONOTRYPELLA Ulrich, 1882. 



("Amer. PaL Bry." Jour. Cin. Nat. Hist. Vol. V, p. 153.) 

 (For generic diagnosis see page 377.) 



Species of this genus closely resemble Amplexopora and Homo- 

 trypa. but with a little practice it is not difficult to distinguish 

 between them. The absence of acanthopores separates them 

 from the first, and the absence of cystiphragms from the second. 



