240 Description of new Lower Silurian Sponges — Ulrich. 
portions of the surface in a curved direction. A limited num- 
ber of " oscula " distinguished from the ordinary canals by 
being larger and surrounded by radiating channels, occasion- 
ally present. 
Sponge skeleton between the canals of variable thickness, 
sometimes appearing nearly solid, at other times composed of 
loosely interwoven spicule libers. None of the specimens show 
the spicules in a satisfactory manner. From the traces seen 
it would appear that they are mostly very small and of the 
three-rayed type. Type : //. suhramosa, n. sp. 
^ This genus is related to the Di/staGtospoiu/ia'^. A. Miller, 
differing from species of that genus chiefly in the erect and 
subramose habit of growth. The four or five species of Mil- 
ler's genus known to me are all parasitic or form amorphous 
masses. 
HETEROSPONGIA SUBRAMOSA. n. sp, 
Sponge subramose, occasionally palmate ; branches more or 
less flattened, from 9 to 13 mm. thick, and 11 to 30 mm. 
wide. The largest specimen seen is 65 mm. high and 45 mm. 
wide. Surface generally even, exhibiting the rather irregu- 
larly distributed canal apertures. These are generally of very 
unequal sizes, though on limited portions of the surface, both 
their distribution and size may be fairly regular. The aver- 
age diameter of an aperture is nearly 0.7 mm., with about 5 in 
5 mm. The width of the interspaces between the canal mouths 
is equally variable, the extremes being 0.2 and 1.2 mm. The 
sponge skeleton is composed of more or less loosely interwov- 
en spicule-fibres, but in the usual state of preservation the 
inter-canal spaces appear quite solid and structureless. In 
none of the specimens are the spicules sufficiently well pre- 
served to make their determination a matter be3'^ond dispute. 
Formation and locality : Upper and perhaps middle beds 
of the Cincinnati group. The best specimens come from 
' This generic and four specific names (subramosa, knotti, aspera 
and nodidosa), were proposed in my Catalogue of Cincinnati group 
fossils, published in 1880. Being unaccompanied by either descrip- 
tions or figures, these species cannot be considered as established. 
The publication of mere ms. names is no more binding to the author 
of such names than to other authors who may have no means of learn- 
ing what the names apply to. This being the first adequate publication 
of the genus and species, their date of publication is necessarily the 
same as that of this issue of the "Geologist." The same is to be 
said of Streptospongia and its species labyrinthica . 
