382 Mr. C. Wachsmuth on the Internal and 
mouth. He further suggested that the food was conveyed by 
the open food-groove to the inner cavity through the arm- 
openings at the base of the arms, by means of subtegminal 
channels along the inner surface of the vault. 
Dr. Liitken, fully confirming Dr. Schultze’s observations, 
gives a full description of the ducts and subtegminal galleries, 
and compares these with the covered food-grooves in Hypo- 
mene Sarst, expressing the opinion that the galleries under- 
neath the summit, which he considered to be closed at the 
bottom and thus transformed into ducts, were food-passages. 
Meek and Worthen describe and figure, in the Illinois Geo- 
logical Report, vol. v., from my former collection, now in the 
Museum of Comparative Zoology at Cambridge, several speci- 
mens of well-preserved digestive organs, and also an Actino- 
ertnus proboscidialis, in which askeleton of tubular canals pro- 
ceeds from a point below the central axis of the vault to the 
arms. There are in that specimen five main tubes which bi- 
furcate midway toward the arm-bases, each division bifurcating 
again, sending a branch to each one of the twenty arms of 
that species. ‘The main tubes and branches are constructed 
on their lower side of alternating plates, upon which, on either 
side, a second row of minute quadrangular interlocking plates 
is attached, longitudinally arranged, thus covering the tubes. 
The upper rows of plates are not preserved in this specimen ; 
but I have found them in two specimens of Sérotocrinus, 
which I obtained recently, in which they are well preserved 
and in place. The condition of the specimen, as Meek and 
Worthen remark, leaves but little doubt that the tubes form 
through the arm-openings of the calyx a continuation of 
the arm-furrows. In removing parts of the vault, I unfortu- 
nately broke the upper part of the fragile skeleton ; but enough 
is preserved to prove that the five main tubes did not connect 
directly with each other, but communicated at their upper end 
(separately, asit seems) with an annular vessel of which traces 
are yet preserved. Sucha vessel was found in wonderful pre- 
servation in a specimen of Acténocrinus Verneuilianus, Shum. 
The radiating canals were here not preserved ; but the little 
openings through which they communicated are plainly 
visible in the circular organ. There are, at the lower side of the 
ring, which is composed of minute interlocking plates, five other 
small openings, which, alternating with the former ones, were 
apparently in connexion with organs of the interradial 
system (communicating perhaps with a circulatory system). 
‘Lhe whole upper part of the stomach is here placed within the 
ring—differing in this particular from <Actinocrinus probosci- 
dialis, in which only a spiral alimentary tube passes out from 
