416 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The branching of this species is such as to produce an irregular 
arborescent form, indicating that the corallum grew upright. The 
corallites seldom grew perfectly cylindrical and erect, almost always 
having a more or less sinuous or irregular outline. The new buds 
were usually given off at an oblique angle. 
Twelve zooids occur on the type specimen (PI. 1 , fig. 1), but 
additional ones probably existed on the broken basal portion of 
this specimen. 
Formation and locality. This species is common in the Hamil¬ 
ton (lower) shales of Eighteen Mile Creek and vicinity in Erie 
County, N. Y. It also occurs in the Marcellus shales and lime¬ 
stones at Lancaster, Erie Co., N. Y. Named in honor of Dr. Robert 
T. Jackson of Harvard university. 
Ceratopora distorta, sp. nov. PI. 3, figs. 1-13. 
Description. Corallum erect or prostrate, frequently and irregu¬ 
larly branching. Corallites irregular in outline, often much distorted, 
cylindrical when perfect. Basal portion of corallites usually more 
or less constricted; calicinal portion frequently inflated. Lines of 
growth irregular, costae faint. Buds diverging at all angles, con¬ 
nected with the parent internally during the earlier stages of 
growth. 
Cysts moderately coarse, trabeculae numerous, well developed, 
and disposed in vertical rows, of which from sixteen to twenty have 
been counted in different individuals. 
This species is much smaller than C. jacksoni , and has a much 
more irregular growth. When the corallum grows prostrate, the 
under side is usually more or less flattened, and not infrequently 
irregular, subradiciform epithecal prolongations occur, as if for 
attachment (PI. 3, figs. 1, 3, 6, 13). In a few cases, the corallum 
has been found growing upon foreign bodies, and in some of these, 
where the corallum was attached to a specimen of Taeniopora, its 
flattened under side conformed accurately to all the irregularities of 
surface of the bryozoarium, even to the extent of reproducing the 
pores in reverse. When prostrate, the lines of growth became 
oblique, and the calyx turned upward, as is characteristically the 
case in C. dichotoma. In one of the specimens (PI. 3, figs. 9, 10) 
a single bud is given off, some distance below the calyx; this bud 
