214 The American Geologist. October, 1895- 
"Revision of the Paheozoic Crinoidea,"* Messrs. Wachsmuth 
and Springer alluded to the fossils as "arm-fragments," and 
in their privately issued "Index" the name was printed in ital- 
ics, as being invalid. 
Now, I have little doubt that the fossils in question are not 
arm-fragments but stem-fragments, and that they belong to 
the same genus as the fossils also described by Prof. Hall as 
arms, under the name 3fyelodactylus, and correctly described 
by J. W. Salter as stems, under the name Herpetorriniis. A 
detailed account of the literary history of those names and a 
minute description of the structure of those fossils was given 
in my "Crinoidea of Gotland. Part I. Crinoidea Inadunata"f 
on pages 36-52. It is therefore needless to repeat here the 
reasons for preferring the name Herpetocrinus or for regard- 
ing the ordinary specimens as portions of stems. I will merely 
point out the reasons for a reconsideration of the status of 
Brachiocrinus. 
That the remains are not arms follows from the fact th^t 
there is, as shown on plate VI, figures 1 and 3f/, of Prof. Hall's 
work, no ventral ambulacral or food groove on the main stem, 
while the supposed pinnules (tentacvila of Hall) are stated to 
be "without any appearance of a groove or canal on the inner 
side." Farther, our present knowledge does not permit us to 
imagine a solitary arm, "without any appearance of an artic- 
ulating surface or point of attachm3nt to any other body,"^ 
but terminating "below in a rotinded condyle;" "as if the 
arm, as it now occurs, had had an independent existence." 
On the other hand, the remains agree in essential structure 
with the stems of other crinoids. The tentacula, or cirri as 
they should now be called, are round in section, "with a linear 
foramen" or axial canal, which in plate V, figure 7, is seen to 
pass into the main stem, where it doubtless joins an axial canal 
in the stem. This latter, it is true, is neither mentioned in thfr 
text nor shown in the section (plate VI, figure 3a) ; perhaps, as 
in many undoubted specimens of Herpetocrinus^ the axial canal 
has been obliterated by the processes of petrifaction. The 
rounded condyle at the distal end of the stem is also not 
without parallel in other crinoids, e.g., Calceocrinvs and 31 il- 
*Part II, p. 229, Proc. Acad. Nat. Sci., Philadelphia, 1881, p. 403. 
tK. Vet. Akad. Handl., Bd. xxv. No. 2, Stockholm, 1893. 
