1 40 The American Geologist. September, 1900 
Fig. 9, Aulocrimis agassizi. This figure was drawn by 
Mr. Westergren from a splendid specimen — perhaps the fin- 
est of this extraordinary form. It was found and 'cleaned by, 
myself. The structure being unusual, and, I not knowing 
what to expect, the part of the ventral sac exposed by the 
breaking off of some of the arms was freed from the adherent 
matrix under a magnifier. While doing so I observed the 
pores throughout almost the whole length of the sac, and the 
pipe-like anal tube as well, located at the middle of the sides 
of each hexagonal plate. Mr. Westergren was instructed to 
draw the pores in his figure, but they were so plain that it was 
not necessary to give him any special directions as to their 
position. Whatever may be the theoretical reasons why it 
should not be so, his drawing is absolutely correct. Four 
uther specimens of this species show the pores, with perfect 
distinctness, in the same position. As this figure is the main 
point of attack, I have had Mr, Blake make a very careful 
drawing from another specimen, which has lost the anal tube, 
but which shows the pores in the sac almost as well as the 
former one. This is made natural size (PI. XVI, fig. 11), 
and he has also drawn one plate and parts of adjoining ones, 
enlarged 4 diameters (PI. XVI, fig. 12). From these it will 
be seen, beyond the slightest doubt, that the pores invariably 
occupy the middle of the sides of the hexagonal plates — ex- 
actly where Mr. Bather says they are never found. The sur- 
face of this sac is conspicuously marked with nodes, which 
occupy the middle of the plates. The pores, although not of 
large size, are readily observable without a glass, being filled 
with a dark infiltrated matrix different in color from the sub- 
stance of the plate. 
I have no doubt that Mr. Bather, impelled by the result 
of the minute study of certain English and Swedish speci- 
mens of Cyathocrinidae, became thoroughly convinced that his 
understanding of these structures was the only correct one — 
not only for the specimens in which he had seen them, but 
for all others. A notion once deeply rooted in the mind is 
not easily eradicated, and it is the "unfortunate experience" 
of most of us that it often influences not only our judgment, 
but our observation also, so that we see things not as they 
are, but as we think they ought to be. Mr. Bather would no 
