BRYOZOA. 319 
Leptotrypa claviformis,. ] 
LEPTOTRYPA CLAVIFORMIS, 7. Sp. 
PLATE XXVII, FIGS. 20 and 21. 
Zoarium growing around and beyond one or more segments of Arthroclema and 
Helopora into simple club-shaped forms varying from the smallest figured to one 
that is 28 mm. long and 1.5 to 2.5mm. in diameter. Some of the specimens have one 
or two short lateral branches, in which cases the supporting body was a twig of 
Arthroclema with lateral segments in place. Zocecial tubes growing about the axial 
body very much as in ordinary ramagse forms they grow about an imaginary center; 
diaphragms abundant except in the outer or direct portion; walls thin. Zocecial 
apertures subangular, nearly uniform in size, there being no appreciable clusters of 
large cells; without apparent arrangement, about fourteen in 3 mm. What may be 
mesopores, but more likely are merely young zoccia, are scattered among the 
ordinary tubes. At intervals, however, they seem to be more numerous than usual. 
Many, perhaps the majority, of the angles of junction are thickened and occupied by 
projecting acanthopores. 
In a general way, this species may be said to fall under Leptotrypa, but I 
am more than inclined to doubt that it belongs there. The interior of the speci- 
mens sectioned is but illy preserved, the finer details of structure being quite 
obscure. Some of the specimens remind of Petigopora, Ulrich, and it is here that 
better sections will probably cause us to refer them. 
Formation and locality.—Rather common in the middle and upper thirds of the Trenton shales 
at St. Paul and Minneapolis. 
Mus. Reg. No. 8132. 
Family CERAMOPORIDA, Ulrich. 
Genus SPATIOPORA, Ulrich. 
Spatiopora, ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 155, and 1883, vol. vi, p. 166; Foorp, 
1883, Contri. Micro-Pal. Cambro-Sil. Rocks, Can., p. 20;- ULRICH, 
1890, Geol. Surv. Ill., vol. viii, p. 381. 
Zoaria forming thin parasitic crusts upon foreign bodies, the shells of Orthoceras 
being the most favored. Surface even or with monticules. Zocecia short, with 
direct and more or less irregularly shaped apertures. Lunarium scarcely perceptible 
even in thin sections. Mesopores very few, usually absent, when present occurring 
chiefly as “macul.” Interspaces often with large blunt spines (? acanthopores). 
Walls of zocecia moderately thin, with the characteristic structure pertaining to the 
family. 
Type: S. aspera Ulrich, 
