EEPORT ON THE CRINOIDEA. 133 



the arms and pinnules ; while remains of their sarcodc 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 egg masses ; ^ and he supposes " that it has been introduced either as 

 an egg or as a larva, and has undergone its development parasiticaUy where it is found." 

 The same explanation will probably account for the frequent presence in the anal tube 

 of Actinometra jukesi and Actinometra strata from Cape York of an Isopod [Anilocra) 

 nearly half an inch long (PI. LV. fig. 1). Either 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 A ntedon escJirichti which have been cut 

 into sections ; but though one or two accomplished zoologists have examined its remains, 

 I have not been able to learn anjrthing about its affinities. Another equally obscure 

 internal parasite of the Crinoids is a peculiar worm which I first found in some sections of 

 Actinometra jta^rvicirra 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 Comatulse from the same 

 locality. It was first noticed in the coeliac canal of the arms, which it often almost filled, 

 so as to suggest the idea that the egg had been introduced into the body-cavity and had 

 developed in that part of it (PI. LXL 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 coelom. 



The external parasites of the Crinoids ai-e many and various ; though it may be 

 doubted whether some of them can be considered as real parasites, i.e., as living at the 

 expense of the Crinoid. Besides the well known Mijzostovia, 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 Comatida!" 



I 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 larvae had to find a resting-place somewhere.* Various 



1 Phil. Trans., 1866, p. 701. ^ Zeitschr. f. wiss. Zool., 1876, Bd. xxvi. p. Ixxix. 



3 Probably the same as the Isopod above mentioned. 



* The same may be said of an Ophiurid larva, which was attached by its long Pluteus-arms to the soUtaiy stem- 

 fragment of Metacrinus tuberosus from near the Ki Islands (Station 192). 



