rr n r 



broken fiiells, of a finer or coarfer texture, according to 

 the nature of the animal inhabitant; and not prepared 

 by a teftaceous fecretion from the body of the animal, 

 forming a compaft, foiid fubftance, the true cha racier 

 of a fliell. 



Amongfl the Sabellce of Linn.eus many larvce of 

 fub-aquatic flies are placed, feveral of which are to be 

 found in our rivers and ftagnant waters : but thefe, de- 

 riving their origin from winged infers, have no claim 

 of affinity to a Sabella, much lefs to a place in Con- 

 chology. 



We are not aware that any true Sabella is found in 

 frefli-water ; and certainly no winged infeft has yet 

 been difcovered, to perform its change from the larva 

 to the perfeft fly, in fait- water. 



Gmelin has enumerated a great muny Sabell(E, which 

 inhabit frefli-water, principally on the authority of 

 Schroeter; many of which are varieties only of the 

 fame imperfeft infeft, the larva of Ephemera vulgata, 

 fome that of Phryganea, and perhaps other Neuropte- 

 rous infefts. 



The tubes, or cafes, in which thefe larvce are con- 

 cealed, are formed of whatever extraneous matter is 

 near, and which is encreafed as its growth requires : this 

 accounts for the many elegant varieties of fuch tubes. 



Some 



