ELASMIAS. 121 



RETT, Journ. A. N. S. Phila., ix, p. 83, pi. 2, fig. 20. 

 SCHMELTZ, Mus. Godeffroy, Cat. v, p. 90. SMITH, Ann. and 

 Mag. N. H., 1897, xx, p. 521. BINNEY, Ann. N. Y. Acad. Sci., 

 iii, p. 99, pi. 3, f. F (teeth). 



Except in the pale brown color, darkening slightly towards 

 the summit, this form does not seem to differ materially from 

 E. ovatum of Rapa ; but the only published figure of the latter 

 is not sufficiently exact for a critical comparison. Probably 

 E. apertum may be a form or subspecies of ovatum. E. fus- 

 cum is a decidedly darker color than apertum, and has 

 stronger lamellae. E. cernicum also has larger lamellae. Under 

 the microscope the surface of E. apertum shows only very 

 faint and fragmentary spiral lines in some places. 



A typical specimen has been figured by Garrett, and is re- 

 drawn in pi. 30, fig. 2. The parietal lamella is rather strong, 

 and little over a fourth of a whorl long. Length 2.7, diam. 

 2.5 mm. In others of the same lot, somewhat smaller, the 

 parietal lamella is lower. 



Specimens from Huaheine (pi. 30, fig. 3) have the parietal 

 lamella lower than in typical apertum, and the spiral striation 

 more distinct. Length 2.4 mm. 



A series from Sunday Island, Kermadec group (pi. 30, figs. 

 4, 5), the parietal lamella is very low in adults, a little more 

 prominent in the young. Spiral striation barely discernible 

 in places. The largest measures, length 4.5, oblique diam. 2.6 

 mm., with 4^ whorls. An infant with 21/4 whorls (pi. 30, 

 fig. 5, length 1^ mm.) shows relatively stronger lamellae than 

 the adult. There are no palatal plicae at any age. The color 

 is corneous, shading into cream-buff towards the summit. 



Mr. Edgar A. Smith remarks that "the type from Tahiti 

 is a little larger and somewhat browner than the shells from 

 Rotuma, but is similar in other respects." From this it ap- 

 pears that the Rotuma specimens resemble those of the Ker- 

 madecs in color, both being of the tint attributed to E. ova- 

 tum, while Society Island shells have a perceptible tint of 

 russet. 



