410 
ORIGINAL ARTICLES. 
fish is attached to the pseudembryo, the communication between the 
ciliated cavity of the pseudembryo and the ambulacral system of the 
embryo may exist at or near this point, indeed this appears to be the 
case, in some instances, from Muller’s observations on the Bipinnaria 
from Sicily. Near the madreporic tubercle more probably than at it, 
for the dorsal pore, with its calcareous ring, is undoubtedly the 
origin of the madreporic tubercle, and whenever this pore exists 
(Trieste Bipinnaria, Auricularia , Tornaria , &c.),it appears always to 
pass through the perisom, and open to the outside. It seems to 
stand in the same relation to the ciliated sacs of the pseudembryo, 
which it afterwards maintains to the ambulcral system of the star¬ 
fish. 
30. In Asteracanthion violaceus (§ 26.) this pseudembryonic append¬ 
age is undoubtedly perfectly distinct from the madreporic tubercle, 
and, as we shall see hereafter in discussing the development of 
Comatula, the stem of the Crinoids is simply a tegumentary append¬ 
age, and its insertion in no way homologates with the madreporic 
tubercle in the other Echinoderm groups. 
31. Dr. W. Busch* * * § describes the embryology of, if his determina¬ 
tion be correct, the same species under the name of Bchinaster 
sepositus —and he distinctly describes the disappearance of the 
peduncular appendage on the ventral surface of the disk. Busch, 
however, describes a mouth in the centre of the peduncle, between 
the vascular branches. I have little doubt that this is an error of 
observation. The oval granular prominence, whatever be its func¬ 
tion, which occurs in this position in all these forms, is clearly the 
equivalent of the oval patch in the same situation in the Brachiolaria, 
where it co-exists with the pseudostome. 
32. Sars describesf a closely analogous mode of reproduction in 
Aster acanthion Mulleri (Sars), but in this species the peduncle seems 
to be distinctly attached to the ventral surface of the disk. 
33. Desor J describes a mode of development slightly different in 
detail, but on precisely the same plan in an American starfish. In this 
case the peduncle is simple, and depends excentrically from the oral 
surface of De embryo. Desor regards the peduncle as a vitelline 
sac, and believes it to be in direct connection with the digestive 
system, into whose general cavity its contents are gradually absorbed. 
Agassiz § confirms Desor’s observations, but gives no definite opinion 
on the relations of the temporary appendage. 
34. Muller describes11 a minute form which he observed at Nice, 
in 1849, and which comes doubtfully under this category. The spe- 
* “ Beobachtungen iiber Anatomie raid Entwickelung einiger wirbellosen See- 
tliiere.”—Berlin, 1851. 
f Op. cit. 
j Proc. Boston Soc. of Nat. Hist. February, 1848. 
§ “Lectures on Comparative Embryology.”—Boston, 1849. 
|| “ Ueber die Larven und die Metamorphose der Holothurien und Asterien.”— 
Berlin, 1850. 
