38 



''of elevations witliin. wliicli indicated points where tlie 

 '•intruding parasite had been kept out hy tlie oyster 

 "whicli liad deposited new layers of calcareous matter 

 "at these places so as to give rise to the elevations spoken 

 •'of. Besides this, the inner table had. become so weak- 

 "ened at the insertion of the adductor muscles that the 

 ••animal in closing had broken a part of it loose, the 

 '•break having been repaired l)y the deposition of a 

 •'brown horny substance." In such cases, as I have just 

 described, it is clear that serious damao-e mav l)e done 

 to the insertion of the adductor muscle, the perfect in- 

 tegrity of which and power to close the valves must be 

 maintained, or there is a possibility that the oyster may 

 be invad.ed by some hungTy carnivorous neighbor and 

 have its vitals eaten avray without being able to shut out 

 the intruder. In buying '•plants"' it would probably be 

 best to select only such cargoes of oysters as appear to 

 have clean unbored shells, or sucli as are not "worm- 

 eaten," since I am told by a practical oysterman. Mr. J. 

 W. AYrightson. that a bed once planted with oysters 

 which are badly infested with Cliona or the boring 

 sponge, are apt to remain so for some time and that the 

 beds adjoining became infested for the reason that the 

 embryo s]jonges Avhich are thrown off in large numbers 

 from the infested "plants," s^vim about in the water, 

 attach themselves to other oysters commence to grow 

 and to bore. 



The 2:)rotozoan fauna of St. Jerome's Creek presents 

 considerable variety : three species of test-building Co- 

 tliuiuia were noticed, one YaginicoJa, three species of 

 Yorticella or bell-animalcules, free swimming EupJotes, 

 jVassulas : of the latter type an exceedingly elongate 

 form was noticed, with a body almost as slender as a 

 thread-worm. Monads were sometimes noted in profu- 

 sion, though some of these may have been the spores of 

 algae. Amoeboid forms were very few. and the only 

 one which was frequently noticed was a form so nearly 



