28 BRYOZOAN FAUNA OF THE ROCHESTER SHALE. 
other than the heterotrypoid wall structure, is the development of the acanthopores in 
narrow zones, which occur intermittently in the zoarium. The following species exhibits 
this character fairly well, although not so markedly as "In some of the Ordovician forms. 
Stigmatella globata n. sp. 
PL XIV, figs. 6-9. 
Zoarium of rounded masses, globular whore growth occurred about a small, short object, 
and elongate when the zooecia covered a ramose bryozoan or a similar long, narrow body; 
the variation in length of the longer diameter in the specimens studied ranging from 10 
nun. to 20 mm. Zooecia polygonal, 7 in 2 mm., thin walled, generally in contact. Meso- 
pores tew, averaging one to a zooeeium. Acanthopores small and moderately numerous 
when one of the zones is cut by thin sections, but otherwise practically wanting. Dia- 
phragms few in both zocecia and mesopores. 
The most noticeable feature in vertical sections is the development of acanthopores in 
zones averaging 0.35 mm. in length and occurring at intervals of 1 mm. A zoarium of 
sonic size is therefore made up of a number of such intermittent zones. 
The massive zoarium, thin-walled polygonal zooecia, and the occurrence of the acantho- 
pores in zones will serve to distinguish this species, although care must be taken not to 
confound it with the similar zoaria of Diplotrypa walkeri and Lioclema globulare. 
Occurrence, — Not uncommon in the Rochester shale at Lockport and Rochester, N. Y. 
Catalogue number, 35769, U. S. National Museum. 
Kamilv B^TOSTOMELLIIDJE: TTlrich.. 
In point of species this is the most prolific family represented in these shales, no less than 
lift ecu forms, referred to live genera, being found. Most of the species afford excellent 
thin sections, in which the chief character of (he family, the fused walls of the ZOOBCia and 
mesopores. is well shown. 
Genus BATOSTOMELLA Ulrich. 
A zoarium of slender, smooth, ramose branches with small, rounded or oval zoceciaj 
separated by more or le>s numerous mesopores and having usually very numerous acan- 
thopores, characterizes this genus. The mesopores, however, seldom show at the surface, 
since with age they become filled with a calcareous tissue and the surface usually shows 
only solid zocecial interspaces hearing the numerous acanthopores. 
The following species, although the first of the genus in matter of time, is very similar 
to the Mississippian types: 
Batostomella granulifera (Hall). 
PI. XIII, figs. l-f»; PI. XXIV, figs. 10. 11. I'l. XXV, figs. 11, 12. 
Trematoporagramihtcru Hall. Nat. Hist. .New York, Pal. II, 1852, |>. 154, pi. 40A, figs. 9a-e. 
Batostomella granulifera Nickles and Bassler, Bull. U. S. Geoi. Survey No. 173, 1900, p. 180. 
Batostomella granulifera Grabau, Bull. New York State Mas., No. 45, 11)01, p. 164, fig. 61. 
Zoarium of slender, ramose branches, usually about 2 mm. in diameter. Surface smooth, 
hirsute because of the numerous acanthopores. Zocecia rounded, elongate, 8 in 2 mm. 
longitudinally and 10 to 11 transversely. Mesopores moderately abundant, usually closed 
at the surface. Acanthopores numerous, seven on an average surrounding a zoarium. 
Zocecial tubes thin walled in the axial region and thickened in the peripheral, where the 
acanthopores and mesopores are developed, the latter closed, as the surface is approached, 
by a deposit ol tissue. Diaphragms absent in both zooecia and mesopores. 
Several associated bryozoa, notably Acanthoclema asperum (Hall) and Lioclema ramu- 
losum n. sp., resemble this form superficially. Under the definition of the latter their differ- 
ences are indicated, while A asperum may be separated externally by its smaller branches 
and different arrangement of the zooecia, these in young specimens being arranged in quincunx 
lines and elongate-stnate in old examples. Internally the two are of course quite different. 
