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a ees = eee pet ee ee ee ee Cane eee eee ee ee A OR OS 
+, pein SR, Sa ne MR Sa | Coc. oy hg ce ee) Rn oe a a hh eee EE co fk SSP eT 
ee 
Meek and Worthen on Paleozoic Crinoidea. 35 
Platyceras in close contact by its aperture, either with the side 
or the vault of the Crinoid, and not unfrequently actually cov- 
ering the only opening in the vault of the latter, so as to have 
led to the opinion that the Crinoid was in the fe act of devour- 
ing the Mollusk at the moment when it peris 
Amongst the numerous beautiful ssactbencien of Crinoids 
found in the Keokuk division of the Lower Carboniferous se- 
ries at Crawfordsville, Indiana, there is one species of Platycri- 
nus (P. hemisphericus), that is so abundant that probably not 
less than two hundred, and possibly more, individual specimens 
of it have been found there by the different collectors who have 
visited that noted locality ; and, judging from those we have 
seen, apparently about one-half of these were found with a 
moderate sized, nearly straight, or very slightly arched and 
conical Platyceras 5 bef anchor’; attached to one side by 
its aperture, between the arms of the crinoid, and often so as 
to cover the single lateral opening in the vault of the same.* 
From the direction of the slight curve of the apex of the Pla- 
tyceras, it is also evident that it it is always placed in such a 
manner, with relation to the Crinoid, that the anterior side of 
the mollusk was directed u ward, when the vault of the Crin- 
oid was turned in that direction. + A species of Goniasteroid- 
ocrinus (G. tuberosus Lyon & Casseday), found at the same 
locality, also has frequently a Platyceras attached to the top 
of its nearly flat vault, so as to cover the only opening in the 
same. It is worthy of: note, however, that it is always another, 
subspiral, Platyceras (very 8 similar to P. ewquilaterum), that 
we find attached to this Crinoid, so that here at least, it would 
* We at one time tid these shells attached to the side of this Platycrinus, 
to be out of reach of the opening, or supposed mou’ ise we had not seen, 
lateral opening, that such was also the case wi s. e have since seen speci- 
mens, however, showing thatit has a lateral opening, a ftiatatore belongs to the 
group J shea beam so that it is probable these she n cover this opening. 
+ Pr ard Owen has — in his Report sy the Geological Survey of 
Tatiana, p. 304 eS se" frequent occurrence o: of a Platyceras yom to this 
andell and a Shumard have also figured in their paper entitled « Oon- 
PE abet to the of Kentucky,” a specimen of Acrocrinus, with a wt 
similar ee, as toi fae attached to its vault. : 
Amongst all the Crinoids found at Burlington, Iowa, we are aware of but asin- 
gle instance of one being found with a Piatyceras attached, and that is a specimen 
pd ee ventricosus in Mr. Wachsmuth’s collection, which has a crushed 
a Platyceras connected with its vault, 
