Pulmonifera of 3faine. 



31 



many places in Maine, and also from Anticosti, has not as yet 

 brought to light any satisfactory characters by which to dis- 

 tinguish this species from its European representative. I offer a 

 few differences which seemed to hold good in a majority of cases, 

 with the hope that it may stimulate others to continue these investi- 

 gations, believing that with extensive suites of individuals from 

 both continents, certain marked and constant characters will 

 be discovered between the two species, which will plainly 

 indicate their non-identity, laying aside all geographical con- 

 siderations. 



The two figures here giv- 

 en, represent the apertures 

 of an American and an 

 European specimen. The 

 majoiity of American speci- 

 mens examined, resembled 

 figure 79, and the majority 

 of European specimens ex- 

 amined, resembled figure ^^0- 80. Fig. 79. 

 80. Our specimens in nearly all cases were larger, possessing one 

 more whorl ; the color of the foreign specimens was different 

 and darker than ours ; the European specimens were more solid 

 and opaque, while ours were lighter in texture and more trans- 

 lucent ; the foi-m of the aj^erture as seen by the figures is broader 

 in the American specimen, from the bulging out of the lower 

 portion of the labrum, and by the labrum curving out more at 

 the suture. The columella which is quite parallel with the axis 

 in the American shell, is slightly oblique in the European species. 

 Mr. W. Thomson in a paper on the dentition of British Pulmoni- 

 fera, (Annals and Magazine of Natural History, second series, 

 Vol. 7,) gives a drawing of the central and first lateral plate of 

 Zua lubrica, with the number of rows, and the number of plates 

 in a row composing the palatal membrane, thus, 80 rows, 40 in a 

 row, total 3200. An American specimen examined had 90 rows, 

 with 43 in a row, total 3870. Figure 83 represents a fac simile 

 of his drawing of central and lateral plate of Zua lubrica. Fig- 

 ure 84 represents the same plates of Zua lubricoidea. We do 



