282 Mr. Swainson's Monograph 



variation in its length, sometimes being shorter than tlie aperture, 

 sometimes of equal length, and in other specimens considerably 

 longer. The following characters, however, belong equally to all 

 these varieties. The spire is covered by a thick coating of enamel, 

 which unites to a transverse, marginated band of the same, on the 

 upper parts of the body whorl. At the base are two oblique, 

 marginated, and thickened belts ; the varix of the pillar is strait and 

 deeply striated ; the aperture moderately effuse, and the margin 

 of the outer lip entire. 



The distinction which M. Lamarck has made between his A. 

 buccinoides and subulata, rests entirely on the relative length of 

 their spires; while on their sculpture he is entirely silent. He 

 refers to the figures in the Ency. M^th. (tab. 393. 1 and 5.) 

 for both, and were we to judge alone from these, (which are tolera- 

 bly correct,) we should certainly be inclined to believe they repre- 

 sented two distinct species ; but a series of specimens now before 

 me, by the progressive developement of the spire, unites the two 

 extremes of length so completely, that I feel persuaded they are 

 varieties of one species. This transition, indeed, may be seen by 

 consulting the following authors, in the series here set down. 

 Ency. Meth. 393. 1. Sowerby, Ancilla, f. 2, Lister, 1034, 8. 

 Ency. Meth. 393. f. 5. The references made by Lamarck to Knorr, 

 2. tab. 43. f. 18. I have no means at present of consulting. 



10. Ancillaria obtiisa. Sp. Nov. Mihi. 



A tests ovala flavescente, infrii riifa ; spira bevi, crassa, ohtvi&, cattaned ; 

 striis cohimell<B obsoletis. 



Shell ovate, yellowish, beneath rufous ; spire short, thick, obtuse, chest- 

 nut ; striae on the pillar obsolete. 



This is a recent species, hitherto undescribed, and so closely does 

 it resemble the figure of A. glandiformis, given at pi. 393. f. 7. of 

 the Ency. Meth. that it might be almost assimilated to that shell, 

 but for the danger of uniting recent and fossil species without very 

 minute examination ; this I am at present unable to do, not having 

 a specimen of Glandiformis in my own collection. 



The spire of the A. obtusa is little more than half the length of 

 the aperture, and is rendered very thick and almost shapeless, by a 



