Occasional Papa's of the Museum of Zoology 59 



spiral sculpture always present ; higher but more compressed 

 than in megacheilos; surmounted by growth sculpture which 

 is developed into hea\T, elliptical bosses; the last give the 

 shell a granulate appearance. Earlier whorls : distinctly can- 

 cellate, but without definite bosses or cusps at the intersec- 

 tions. Peristomal callus : heavier than in megacheilos. Other 

 characters as in megacheilos. 



Table VI. Dimensions of Tudor megacheilos and T. pilsbryi 



Measurements 



Shell Aperture Operculum Whorls 



alt. maj.diam. min.diam. alt. diam. long wide 



male 14.9 67( 9.9) 54(8.0) 51(7.6) 96(7.3) 37(5.5) 80(4.4) 4 

 female 



(t}T)e) 18.3 67(12.3) 53(9.6) 50(9.2) 100(9.2) 34(6.3) 78(4.9) 4% 



