614 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



though not feeding directly upon the tissues of the host; or (3) while living 

 externally upon the surface of the body and not feeding directly upon the tissues 

 or fluids of the host are more or less permanently fixed in position and cause more 

 or less extensive malformations, sometimes becoming encysted. 



1. Animals which live upon the tissues or the body fluids of the crinoids. 

 (a) Internally: 



Undetermined internal worm (?myzostome) in the ovary. 



Parasitic worm of doubtful affinities. 

 (6) Externally: 



Laphystio-psis iridometrce. Sabinella ptilocrinicola. 



Parasitic Ostracod. Sabinella capillastericola. 



Collocheres gracilicauda. Sabinella, spp. 



Stilifer bathymetrcB. Melanella capcnsis. 



Stilifer, spp. Melanella, spp. 



tStylinu cornatulicola. H enrnpeiropsis antedonis. 



2. Animals which are internal, though not feeding directly upon the tissues 

 of the host : 



Enterognathus comatulcB. Holotrichous infusorian. 



Certain myzostomes. 



3. Animals which, while living externally upon the surface of the body and 

 not feeding directly upon the tissues or fluids of the host, are more or less perma- 

 nently fixed in position and cause more or less extensive malformations, sometimes 

 becoming encysted. 



Many myzostomes. 



II. Semiparasitic Commensals: Animals which feed upon minute organisms 

 and have to a greater or lesser extent adopted the habit of sucking up the food 

 particles from the streams flowing down the ambulacral grooves of the crinoid to 

 the mouth, or of temporarily entering the digestive tube and feeding upon the 

 contained matter: 



Synalpheus comatularum. Girolana lineata. 



Synalpheus stimpsonii Tridldivensis. Gyclotelson purpureum. 



Syimlpheus carinatus binongcensis. Undetermined crustacean. 



SyTudpheus brucei. fOphiactis deUcata. 



Synalphevs, spp. Ophiomaza cwcaotica. 



Periclhnenea commcnsdlis. Ophiomaza oacaotica var. picta. 



Periclimenes eomutus. Ophiomaza obscura. 



Penclimenes ceratophthalnitis. Ophiomaza c.oiaphracta. 



Periclimenes brocketti. Ophiomaza mmrens. 



Periclimenes pottsi. Ophiorcthiops unicolor. 



Pontoniopsis comanthi. Ophiocethiops clegans. 



Galathea elegants. Ophiophthirius actinometrce. 



Galathea inflata. Ophiosphtera insignis. 



Galnthea minuta. Polyn-oe jninuta oculata. 



Anilocra, sp. Polynoe crinoidicola. 



Most myzostomes. 



