BRYOZOA. 317 
Leptotrypa hexagonalis.] 
from the types of growth mentioned in the description, Numerous species of both 
genera are known and several of Leptotrypa from the Trenton beds of Minnesota, 
True Amplexopora, however, is first met with in the Utica.* 
LEPTOTRYPA HEXAGONALIS Ulrich. 
(Not Figured.) 
Leptotrypa hexagonalis, ULRICH, 1890. Geol. Surv. Ill., vol. viii, p. 455. 
Original description: “Zoarium forming parasitic expansions less than 1 mm. 
in thickness, spread upon Orthoceras and Hyolithes. Surface smooth. Clusters of 
cell apertures of almost twice the usual size are arranged in diagonally intersecting 
rows; these clusters are about 3 mm. apart, measuring from center to eenter. Zocecia 
regularly hexagonal in shape, sometimes a little elongated, seven, measuring longi- 
tudinally, almost nine, diagonally, in 2 mm.; diameter of the smaller 0.2, of the 
larger 0.35 mm. Acanthopores prominent on the surface when well preserved.” 
This species occurs almost invariably as a delicate lace-like expansion upon 
Hyolithes baconi Whitfield. This fact, together with the markedly hexagonal shape 
of the zocecial apertures, renders it an easily recognized species. 
Formation and locality.—Rather rare in the limestone at Minneapolis, Minnesota. The types are 
from equivalent beds (‘‘ Lower Blue”) at Mineral Point, Wisconsin, and Calhoun county, Illinois. Other 
localities are Janesville and Beloit, Wisconsin. 
Mus. Reg. Nos. 7551, 7557, 7595. 
LEPTOTRYPA INFORMIS, 2. Sp. 
PLATE XXVII, FIGS. 22 and 23. 
Zoarium forming parasitic patches or lump-like growths upon foreign bodies, 
varying considerably in size and from | to 5 mm. in thickness. At other times 
apparently free, with a wrinkled epitheca beneath. Surface without monticules, 
nor are the clusters of large cells very conspicuous except in a few cases where the 
zocecia forming them are separated by a limited number of small cells. Zowcial 
apertures polygonal, thirteen or fourteen of the average size in 3mm. Walls very 
thin, in vertical sections sometimes appearing as though made up of alternating 
horizontal bands of light and dark shades. Acanthopores more or less prominent 
at the surface, varying some in size, restricted to the angles of junction, one-half of 
which are occupied by them. Diaphragms complete, on the whole rather remote 
and irregularly distributed, the intervals between them varying from one to four 
times their diameter. 
*Trenton species have been placed under Amplexopora by both Mr. A. H. Foord and myself, but a re-examination 
has convinced me that the species in question are more likely aberrant types of Batostoma, where I would now place 
them, d 
