GENUS DOLIUM. 



to be connected with my second group ; and which, uniting all 

 the characters observed in the Tuns, ought naturally to take its 

 place among them, under the name of DOLIUM latilabre. In 

 the same work this author gives, under the name of MALEA 

 crassilabris, a shell which I consider as a variety of the first ; 

 the only differences which this author himself has found, consist 

 in the smallness of the shell, in the spire, which is a little more 

 prominent, and in the thickness of the right lip, characters 

 which appear to me too little specific, and too variable to deter- 

 mine its separation as a species. We shall find also in this 

 series the DOLIUM pomum, which approaches exceedingly to 

 the DOLIUM latilabre in the form of its aperture, in the ridges 

 which exist upon the columella, and particularly in the right lip 

 which is widened, and has, internally, folds, or very strongly 

 prominent denticulations. 



The animals of the Tuns are in general strongly colored, and 

 painted with different tints which form bands and spottings upon 

 their entire exterior. These animals are often found in rapid 

 waters, and upon pebbly bottoms ; their motions are quick. The 

 species seen upon our coasts appear towards spring, and in 

 summer : the other species inhabit warm climates. 



A. Species with the right lip always thin and undulated. 



1. DOLIUM PERDIX, LAM. The Partridge Tun. 



(Collect. MASS. LAM.) LIST., Conch., t. 984, fig. 43. 



PI. V, fig. 9. 



D. testa ovato-oblonga, inflata, tenui, fulvo-rufescente, maculis albis 

 lunatisque seriatim notata ; costis convexiusculis, confertis ; spir& exserti- 

 uscula, conica. 



Shell ovate-oblong, ventricose, pretty thin, of a reddish 

 brown color, pleasingly varied with white spots in transverse 

 series, for the most part semi-lunar, and more or less distant ; 

 spire slightly projecting, conical, pointed, composed of from 

 five to six whirls which are furnished with numerous ribs, 



