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. 



(b) Externally: 



Laphystiopsis iridometrce. Sabinetta ptilocrinicola. 



Parasitic Ostracod. SabineUa capillastericola. 



Collocheres gracilicauda. Sabinella, spp. 



Stilifer bathymetrcB. Melanella capcnsis. 



Stilifer, spp. Melanella, spp. 



Stylina comatulicola, Hemispeiropsis antedonis. 



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

 of the host : 



Enter ognathus comatulce. 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. Cirolana lineata. 



Synalpheus stimpsonii mdldivensis. Cyclotelson purpureum. 



Synalpheus carinatus bmongcensis. Undetermined crustacean. 



Synalpheus brucei. fOphiactis delicata. 



Synalpheus, spp. Ophiomaza cacaotica. 



Periclimenes commen-salis. Ophiomaza cacaotica var. picta. 



Periclimenes cornutus. Ophiomaza obscura. 



Periclimenes ceratophthalmus. Ophiomasa cataphracta. 



Periclimenes brocketti. Ophiomaza mcerens. 



Periclimenes pottsi. O phiocc.thwps unicolor. 



Pontoniopsis comanthi. Ophio&thwps clegans. 



Galathea elegans. OphiophtMrius actinometrce. 



Galathea inflata, Ophiosphaera insignis. 



Galathea minuta. Polynoe. minuta ocvlaka. 



Anilocra, sp. Polynoe crinoidicola. 



Most myzostomes. 



