PISOCRINIDAE 
71 
Order INADUNATA Wachsmuth and Springer 
Crinoidea with a rigid calyx in which the brachials are free (or sometimes loosely 
connected) above the radials. No interradials or interbrachials except at the 
POSTERIOR SIDE, AND BRACHIALS NEVER NORMALLY INCORPOIL\TED IN THE CALYX. PlATES 
OF THE CUP UNITED BY CLOSE SUTURE. MoUTH SUBTEGMINAL ; FOOD-GROOVES SUPRA- 
TEGMINAL, BUT MAY BE CLOSED BY FIXED AMBULACRAL PLATES. ArMS WITH OR WITHOUT 
PINNULES. 
Of this order by far the most important development resulting from the present collec- 
tions is in the Calceocrinidae, which in their peculiar anatomy stand out apart from all other 
crinoids. This has not only furnished the material for the first satisfactory comparison of 
European and American forms, but also has produced an example of evolutionary modifi- 
cation, with the process clearly visible, that is without precedent among the crinoids. This 
succession involves a long course from the Ordovician to the Lower Carboniferous, and in 
the somewhat elaborate treatment of the family which its history has dictated, it has been 
found necessary to include rather full discussion and illustration based upon those epochs in 
addition to the Silurian. 
Another strange form, Myelodactylus, with its coiled bilateral stem, has proved to be 
prolific in instructive material, revealing close relationship with some of the European species. 
The genus Gissocrinns, hitherto known only from Gotland and England, is represented here 
by at least two species, one of them of a type decidedly new and distinct. 
Among the Larviformia, the puzzling genus Zophocrinns is now illustrated more com- 
pletely than ever before, and doubtful points of its structure cleared up ; and the mysterious 
Mysticocrinus re-figured and described. The inconspicuous and widely distributed Pisocrinus 
is represented by such a wealth of new material as to require a complete review of the numer- 
ous species already known. 
Suborder LARVIFORMIA Wachsmuth and Springer 
Monocyclic (with exceptions). Calyx above the base consisting only of 
radials and orals, without anal plates, and usually without visible ambulacra; 
plates immovably united by close suture. Arms non-pinnulate, simple and uni- 
serial. Tegmen when known consisting chiefly of orals. 
Family PISOCRINIDAE Angelin 
Basals three to five; radials five, unequal, r. post, and r. ant. compound, 
1. post, and ant. much the largest, 1. ant. reduced. 
