Se ee yc ty 0) ea ear a 
Meek and Worthen on Paleozoic Crinoidea. 23 
13’, and of e1, 23° 13’, ne The cleavage as above deter- 
mined measures 24° 40’ o This result Spee so extra- 
ordinary, that a piece was iene out of the plane g', ona 
crystal upon which there could be no mistake as to the exact 
location of these cleavages ; for the crystal had the prism well 
defined, with terminal planes, and a basal cleavage. The re- 
sult just given was verified, although the measurement could 
not be so exactly made as upon the first fragment. The zone 
readings were: g', 0°; cleavage, 24°; e', 67°; e', 114°; g’, 
Lie’ ; “Cleavage, 337° to 340°, It now becomes a matter of 
interest to discover these cleavages upon other members of the 
group. A rounded grain of olivine washed from the lava of 
the Sandwich Islands, was cleaved, and presented a bright sur- 
face judged to be the cleavage plane g'. This 8 gave three reflec- 
tions, the readings for the instrument being: 0°; 6°; 13° 
approximatively. In olivine in lava, also from the Sandwich 
Islands, there were indications of cleavages about the plane g’, 
but they are not well defined, while, parallel to g', this variety 
i readily ; although the surfaces developed are not bril- 
lia 
Besides the interest these cleavages have crystallographi- 
— cally, they may be found to have an important aring, in. com- 
paring some members of this group, which do not occur in 
well defined crystals. 
Art. III.—WNotes on some geod in the Structure and Eee 
of the Paleozoic Crinoidea ;* by F. B. Merx and A. H. Wor 
THEN, of the State Geological Survey of Illinois. 
THrovuGH the kindness of Mr. Charles Wachsmuth, of Bur- 
lington, Iowa, we have recently had an opportunity to examine 
some unique and exceedingly interesting specimens of Carbon- 
iferous Crinoids, presenting parts of the structure of these ani- 
, in some instances, never before observed, so far as we are 
at this time informed. In a few instances, these specimens 
show internal organs entirely free from the matrix, and although 
like all the other solid parts of these curious creatures, composed 
of numerous calcareous pieces, really surpassing in delicacy of 
structure the finest lace-work, and so frail that a touch, or even 
a breath, might almost destroy them. Some of these s speci- 
mens we propose to notice here, but, before proceeding to do 
* From the Proceedings of the Acad. Nat. Sci. Philadelphia, 1869, p. 323. — 
3 publication, 
+ By Mr. Wachsmuth’s permission, we have prepared for fu' ture 
jaune of all of these instructive specimens. 
