LEPRALIA EDAX. 313 



interspersed amongst the ordinary cells, and constitute a 

 marked characteristic *. 



Habitat. Usually on small univalve shells {Natica, 

 Tumtella, Trochus, &c.) from moderately deep water. 



Localities. Plymouth Sound; off Fermain Bay, Guern- 

 sey, iu about 30 fathoms (T. H.) : in one confined area 

 off Guernsey, in 15-20 fathoms, incrusting Trochus Mon- 

 tagui, Wood, Nassa incrassata, Strom, Trophon muricatus, 

 Montagu, &c. (A. M. N.): off the Deadman (C. W. P.). 



Geographical Distribution. Florida, in 49 and 79 

 fathoms (Pourtales). 



Range in Time. Coralline Crag (S. Wood) : Middle 

 Pliocene (Coralline and Red Crag) (A. Bell). 



L. edax is found almost universally investing certain 

 univalve shells, or rather occupying the place of the shell 

 of certain Gasteropod mollusks. For it is a remarkable 

 fact that in all cases the shell which served as the original 

 site of the colony, has disappeared, and its place is filled 

 and its form perpetuated by the crust of the Polyzoon. 

 This is true of fossil as well as of recent specimens. The 

 Lepralia possesses the power of eating away and removing 

 the shell ; and its own zoarium supplies a good and solid 

 substitute for the house which it has supplanted. Busk 

 has noticed (in Crag specimens) , *' that other shells, 

 either entire or in fragments, together with minute peb- 

 bles, are occasionally found imbedded in the parasitic 

 mass " t- 



Smitt describes a form from the coast of Florida, which 



* " The greater avicularia . . . have an inversely spatulate or a flask- 

 shaped form of their aperture, with its linear produced tip pointing ob- 

 liquely upwards." — Flor. Bryoz. pt. ii. page 65. 



t Crag Polyzoa, p. 60. 



