BRYOZOA. ppall 
Monticulipora (?) cannonensis. ] 
been lateral (see transverse section, pl. XX, fig. 3) is now narrower and produced so 
that it extends nearly across the center of the zocecial cavity. This is shown best 
in tangential sections, parts of two of which are represented in figs. 4 and 6 on plate 
XX. Figure 4 shows the structure immediately beneath the surface, with small 
acanthopores and numerous smaller pores in the walls and cystiphragms. In figure 
6, showing the appearance at a slightly lower level, the walls are thinner and the 
acanthopores apparently wanting. Figs. 15 and 14 (plate XX) represent tangential 
and vertical sections of a Kentucky specimen of this species in which we note an 
unusual condition, namely, in some parts of the axial region there is a total absence 
of both diaphragms and cystiphragms. In other parts of the same section, however, 
these structures are developed in the usual manner, so that it is allowable to assume 
that their occasional absence is merely an abnormal condition. The tangential 
section represents a condition very nearly intermediate between figs. 4 and 6 of the 
same plate. 
In many respects this species resembles Atactoporella ramosa, occurring in the 
bed of shales next beneath, but the surface of the latter is more abundantly spinulose. 
Thin sections, especially tangential, are easily distinguished. The true position of 
the species seems to be nearer the frondescent variety of M. mammulata d’Orbigny, 
described by Nicholson from the Cincinnati rocks under the name of M. molesta. 
Formation and locality.—Galena shales at several points near Cannon Falls, Minnesota, and at 
Decorah, Iowa. In Kentucky the species occurs in the Trenton shales between Burgin and Danville, 
and at Frankfort. 
Mus. Reg. Nos. 7631, 8035. 8048, 8062. 
MonricuLipora (?) CANNONENSIS, ”. Sp. 
PLATE XX, FIGS: 10-12. 
Zoarium ramose, branches subcylindrical, 6 to 9 mm. in diameter, surface even, 
without monticules, but exhibiting the usual clusters of large cells. These, however, 
are inconspicuous in this species. Zocecia angular, with thin walls, about twelve in 
3mm. Mesopores and acanthopores apparently wanting, the occasional small cells 
wedged between the ordinary zocecia being merely young or abortive. 
Internal characters: All that is known of these is shown in figures 10 to 12 on 
plate XX. The characteristic features are (1) the greatly crowded diaphragms and 
cystiphragms, (2) the presence of the latter throughout the length of the tubes, (3) 
the unusual tenuity of the walls in tangential sections, and (4) the almost total 
absence and exceedingly small size of the acanthopores. 
The generic position of this species is somewhat in doubt. The ramose habit of 
growth, and all the other characters save one, are indicative of Homotrypa. This 
