REPORT ON THE CRINOIDEA. 133 
the arms and pinnules ; while remains of their sarcode bodies occur in the intestine of 
decalcified specimens. Dr. Carpenter mentions the frequent presence in the alimentary 
canal of Antedon rosacea, so as almost completely to choke it, of the body of a suctorial 
Crustacean with its eg masses ;* and he supposes “that it has been introduced either as 
an egg or as a larva, and has undergone its development parasitically where it is found.” 
The same explanation will probably account for the frequent presence in the anal tube 
of Actinometra jukesi and Actinometra strota from Cape York of an Isopod (Anilocra) 
nearly half an inch long (Pl. LV. fig. 1). Hither as an egg or as a larva it must have 
been caught in one of the ciliary currents converging on the mouth from the arms, and 
have then been carried through the digestive tube to the rectum where it remained. 
A third form of parasitic Crustacean is one which I have found encysted in the 
ventral perisome of the disk of some individuals of Antedon eschrichti which have been cut 
into sections ; but though one or two accomplished zoologists have examined its remains, 
I have not been able to learn anything about its affinities. Another equally obscure 
internal parasite of the Crinoids is a peculiar worm which I first found in some sections of 
Actinometra parvicirra that were cut some years ago in the zoological laboratory of the 
University of Wiirzburg. The Crinoid had been obtained in the Philippine Islands by 
Prof. Semper, and I found three individuals acting as hosts to this singular and entirely 
unknown creature, which I have not met with in any other Comatule from the same 
locality. It was first noticed in the cceliac canal of the arms, which it often almost filled, 
so as to suggest the idea that the eg had been introduced into the body-cavity and had 
developed in that part of it (Pl. LXI. fig. 4). I subsequently found it in the visceral 
mass of two other individuals, occupying some of the meshes in the connective tissue net- 
work which fills up the intervisceral ccelom. 
The external parasites of the Crinoids are many and various; though it may be 
doubted whether some of them can be considered as real parasites, 7.e., as living at the 
expense of the Crinoid. Besides the well known Myzostoma, of which I will speak later, 
Willemoes Suhm found four other parasites on one Comatula, all resembling it in 
coloration.’ ‘‘ Es waren das erstens auf dem Kelch sitzende Ophiuriden, zweitens kleinere 
Aphroditaceen, drittens Amphipoden,’ die sich in den Magensack eingebohrt hatten und 
viertens ein Alpheus. Mit Myzostomum also fiinf Parasiten auf dieser allerdings sehr 
grossen Comatula!” 
[have frequently found Ophiurids entangled in the cirri, which is probably merely 
accidental ; while small bivalves, Sertularian Hydroids, Polyzoa, tube-worms, and 
corals (Pl LI. fig. 8) may be attached to the stem, not for any special nutritive 
purposes, but simply because the larve had to find a resting-place somewhere.* Various 
1 Phil. Trans., 1866, p. 701. 2 Zeitschr. f. wiss. Zool., 1876, Bd. xxvi. p, xxix. 
5 Probably the same as the Isopod above mentioned. 
4 The same may be said of an Ophiurid larva, which was attached by its long Pluteus-arms to the solitary stem- 
fragment of Metacrinus tuberosus from near the Ki Islands (Station 192), 
