LINXEAX GENERA OF SHELLS. 



53 



The Teredo Navalis, or ship-worm, insinuates itself into the bottoms of 

 ships, even althougli the oak is perfectly sound, and in a very short time 

 completely destroys it. This destructive creature was originally brought 

 by our vessels from tmpical climates; but has now become an inhabitant of 

 most of the harbours of this island, and is very common in Plymouth Dock 



It was first proved by that learned and very indefatigable naturalist. 

 Colonel George Montagu, in his supplement to Testacea Britaunica, that 

 the animal inhabiting the Teredo, was not a TerebeUa, but an Ascidea. 



Genus ^Q — SABELLA. 



Animal a Nereis, with a ringent mouth, and two thicker 

 tentacula behind the head; shell tubular, composed of particles 

 of sand, broken shells, and vegetable substances, united to a 

 membrane by a glutinous cement. 



Sahella tubiformis.-^Fhte IX. fig. 36. 

 These shells, (if they can be called so) inhabit the sea and fresh water 

 ditches. The Linnean Sabellae are not testaceous shells, but merely cover- 

 ings made up of extraneous substances ; and may therefore fairly be ex- 

 punged from the collection of the Conchologist. They are included in 

 Lamarck's class Annelides, from the formation of the animal. 



TABLE 



OF THE 



LINNEAN GENERA OF SHELLS, 



WITH LAMARCK'S DIVISIONS OF THESE GENERA; 



I. Chiton, 



II. Lepas, 



5" Chiton. //)3 



I Chitouellus./<;i 



Tubicinella/irf2 



Coronula. /p'/ 



Balanus. /oV 



Acasta. 



Creusia. /j 

 1 Pyrgoma./ 



Anatifa. /^y 

 I Pollicipes./4Y 

 I Cineras. /M 6 



Otion. 



III. PHO..S. i- [ Sito^-h/^^MrV. SOLH.. 5/ 



IV. MvA, 3/ 



r Panopaea. /uU 

 I Glycimeris. /UU 



Anatina. ^(Jjf 

 I Lutraria, /if/ 



J pa>-t- . - ■> 



J Amphidesnia, / J/ 

 part. ^^L 



/if 



Corbula 

 Unio. 

 Hyria. 

 L Vulsella 



S Soten. 



Anatina, pari. //f. 



e3 



