142 Tlie American Geologist. September, i900 
tube, but in the dorsal cup." The specimen from which this 
figure was made came from Crawfordsville, Indiana, and 
both the test and matrix are dark, so that it is very difficuk 
to interpret the minute structures. The pits to which he al- 
kides as pores piercing the dorsal cup are very deep depres- 
sions at the angles of some of the plates. Whether they act- 
ually pass through the test I cannot tell from the specimen, 
and I do not profess to give any explanation of them. I 
may here remark generally that the pores are not always 
to be seen in specimens preserving the ventral sac, for two 
reasons, (i) The condition of fossilization. There is a great 
difference in specimens from different localities. The Craw- 
fordsville specimens, which are oftener seen in collections 
than any others in which these parts are preserved, generally 
have the substance of the plates dark colored, and of a rather 
rough granular structure. In these it is difficult to detect or 
draw the fine structures, because there is no contrast between 
the test and the matter with which the pores or other cav- 
ities were filled. Little is to be gained in these cases by grind- 
ing, scraping or cutting — as I have learned to my cost. In 
specimens from Indian Creek, and from Huntsville, the test is 
of a finer and firmer texture, and of lighter color than the in- 
filtrating matter, so that all cavities are well shown by the 
contrast, and the surface of the plates can be accurately clean- 
ed, by both mechanical and chemical means. (2) The pores 
do not as a rule — probably never — occur throughout the en- 
tire sac, but are confined to limited areas. As we usually see 
but one side of the sac in the fossil state, we may often miss 
them for this reason. 
Referring again to our figure 6, the specimen figured did 
not show any pores in the sac. The species is found both at 
Crawfordsville and Indian Creek in excellent preservation — 
especially at the latter locality. Several specimens show the 
ventral sac; but the sac is one of those which are covered 
with a very deep sculpturing, which has made it difficult to 
distinguish pores from mere depressions, such as Mr. Bather 
found in his specimens of Cyathocrinus and Botryocrinns. I 
have now ascertained that the pores are present in this species 
also, and are located on the radial lines. They are quite small 
for the size of the specimens, and lie, not in the grooves 
