80 THE LIFE OF THE MOLLUSCA 



taceans of different sorts (Ismaila and Splanchno- 

 trophus) are to be found on Nudibranchs; another 

 attaches itself to the float of Ianthina, which it 

 matches in colour. Ostracotheres lives in the gills 

 of the Giant Clam (Trtdacna) ; while Pinnotheres 

 takes up its abode within the shells of several 

 different Bivalves, including the great Pearl Oyster, 

 and one species has lately been found in Strombus. 



A quaint little Mite (Philodromus limacum) infests 

 terrestrial Gastropods. It lives in the breathing 

 chamber, and may be seen issuing therefrom and 

 running with great rapidity over the body of its 

 host, but what its connection with the mollusc may 

 be is quite unknown. Another kind of Mite (A tax) 

 is found on freshwater Mussels. 



Clear cases of commensalism on the part of 

 molluscs with other animals are those of certain of 

 the Pelecypods : Modiolavia marmovata lives in the 

 integument of Ascidians ; Montacuta, Lepton and 

 Sciobevetia dwell with Echinoderms. Jousseaumia 

 is commensal in the chamber of a Sipunculid Worm 

 (Aspidosiphon), which is itself commensal in the coral 

 genera Heterocyathus and Hetewpsammia. Lepton 

 squamosum resides in the burrows of Annelids and 

 Crustaceans ; Ephippodonta is commensal in the 

 burrow of a Prawn ; Vulsella lives in the substance 

 of Sponges. The Gastropod Magilus, which takes 

 up its abode in coral masses, and probably supports 

 itself on the Infusoria and other small animals which 



