BATOSTOMELLID^G. 31 
The specimens usually found have elongate polygonal zooecia opening at the surface 
somewhat obliquely. The oldest specimen seen shows the following external and internal 
characters. At the surface the zocecia are direct, thin walled, polygonal, in contact laterally, 
but with the angles occupied by shallow mesopores. Sections show that the zocecial tubes 
are thin walled and flexuous in the axial region and but slightly thickened in the very 
short peripheral zone, where a few mesopores and still fewer acanthopores are developed. 
Not a trace of a diaphragm has been observed in either zooecia or mesopores. Measuring 
lengthwise, 6 to 7 zooecia in 2 mm. 
The resemblance of this species in several respects to Homotrypa confluens Foerste a 
and Homotrypa similis Foord b caused Nickles and the writer to refer it as above. The 
two species mentioned have thin flexuous walls in the axial region and a short peripheral 
zone, both of which are characters of E. solida, but they differ in developing a short series 
of cystiphragms and diaphragms. In spite of this difference in tabulation, these three 
species have much in common and future investigations may show that Eridotrypa and 
this section of Homotrypa are more closely related than the classification now shows. E. 
solida is far from being a typical Eridotrypa, but its combination of characters seems to 
indicate that genus more than any other. A similar species is Eridotrypa appressa Ulrich 
from the Hamilton formation of Illinois and Iowa. 
This species is so different from the associated members of the genus that comparison is 
not necessary. The external characters have already been pointed out and vertical frac- 
tures show the short peripheral region and absence of diaphragms very well with a hand 
lens. Specimens are often found crushed, the thin-walled axial region apparently not 
being able to stand much pressure. 
Professor Hall mentions this as a rare form, but it seems to be quite abundant in the 
collections. 
Occurrence. — Common at Lockport, Rochester, and other localities in New York ; Grimsby 
and Thorold, Ontario. 
Catalogue numbers, 35525, 35526, U. S. National Museum. 
Eridotrypa similis n. sp. 
PI. XII, figs. 10-14; PI. XXVI, figs. 1, 2. 
Zoarium apparently free, consisting of a short, stout basal portion obtusely pointed at 
the lower end and growing upward by dichotomous branching into six or more cylindrical 
stems, usually about 5 mm. in diameter. Surface smooth, the maculae being inconspicuous 
and distinguished by having slightly larger zooecia and more numerous mesopores than 
usual. Zocecial apertures direct, varying from angular to rounded, the shape depending 
upon the number of mesopores present. Walls ridge-shaped at the surface and hence 
appearing thin, but in thin sections they are seen to be considerably thickened. Well- 
preserved specimens show small acanthopores at the junction angles of the walls. Meso- 
pores numerous in the maculse, where they isolate the zooecia, elsewhere usually few and 
placed in the angles between the zooecia. Five to 6 zocecia in 2 mm. 
The external as well as internal characters of this" form are such that the species should be 
recognized with little difficulty. In the immature region the zooecia are thin walled and 
have diaphragms distributed at intervals of about five times their own diameter. In the 
late immature and early part of the mature region one or more diaphragms are inserted 
and are placed about their own diameter apart when more than one are present. The late 
part of the mature region shows no diaphragms. Compared with the zocecia, the mesopores 
are closely tabulated, for here the diaphragms are arranged about their own diameter apart 
throughout the tube length. Tangential sections show that the zocecia are rounded polyg- 
onal in outline and that each is surrounded by a thick ring-like wall composed of fine- 
grained sclerenchymatous tissue. The mesopores usually have no distinct investing wall 
«■ Geol. Survey Ohio, VII, 1895, p. 000. 
bContrib. Micro-Pal. Cambro-Sil., Canada, 1883, p. 10, pi. 2, figs. 2-2d. 
