330 Dr. Maton’s Description of 
ought to be placed, for Linnzus has not made the absence of 
teeth an indispensable character for a Mytilus, and some of that 
genus gape like the Mye at one extremity. 
5. VOLUTA FLUVIATILIS. 
Tas. XXIV. Fig. 13. 
Vorvra testa subovali, pellucida, levi, columella bipliinig 
apertura integra. 
Habitat in America australi, fluviatilis. 
Testa vix à poll. longa, ultra 4 poll. lata, tenera, flavescente-vi- 
ridis, maculis brunneis transversim lineato-notata. Anfractus ro- 
tundati. Spira prominula. - 
6. VoLUTA FLUMINEA. 
Tas. XXIV. Fig. 14, 15. 
VorumA testa obovata, cornea, longitudinaliter delicatissimé 
striata, apertura integra, columella biplicata, apice acuto, bre- 
vissimo. 
Habitat in America australi, fluviatilis. 
Testa magnitudine precedentis, at ventricosior, anfractibus 
magis depressis, apice veró tenuior, colore pallidior, obsolete li- 
neato-maculata, lineis distantioribus. 
These Volué@ are so nearly allied to each other, that I hesitated 
at first to consider them as distinct species; yet the characters 
given above, it is presumed, will sufficiently authorize their se- 
paration. The shape of V. fluviatilis is almost a perfect oval, 
but that of V. flumineais obliquely ovated. This variation might 
be attributed to difference of age, were not the specimens all of 
equal 
