64 THE NAUTILUS. 



SOME NOTES ON THE OLIVIDAE. 



BY CHARLES \V. JOHNSON. 



II. 



OLIVA VIDUA (Bolten). 



Porphyria vidua Bolten, Mus. Boltenianum, p. 34, 1798. 



Oliva maura Lam., Ann. du Mus., XVI, p. 309, 1810. 



As in the case of 0. sericea, both Bolten and Lamarck again refer 

 to the same figures by Martini (Conch. Cab., II, tab. 45, figs. 472 7 

 473). The variation of the species is well shown by Marrat under 

 the name " mauritiana " Martini (Sowerby's Thes. Conch., IV, pL 

 10, figs. 133-140). The figures referred to by Bolten represent one 

 of the extreme variations. What would probably be considered the 

 normal color is represented by the var. sepulturalis Lam. (Marrat r 

 fig. 133). This variety in losing entirely the brown markings be- 

 comes the olive-green or yellowish fenestrata Bolten, or with the 

 dark brown assuming wide, irregular, longitudinal stripes, the var. 

 fulminans Lam., while these stripes suffusing form the dark brownish- 

 black vidua. On the other hand there is a tendency for the shells to 

 become gradually lighter in color than sepulturalis, such forms rep- 

 resenting the var. macleaya Duclos (Marrat, fig. 140). 



It is this latter variety that leads to what is probably one of the 

 most puzzling groups of shells to define specifically that exists. One 

 cannot realize this difficulty from a few shells which usually fall quite 

 readily into one of the numerous species. With over 200 specimens 

 of the group comprising vidua, tigrina and elegans there are some 

 specimens so intermediate in character as to make it very difficult to 

 draw the line. To unite these, however, upon the character of the 

 shells alone, with the meagre data bearing upon their distribution and 

 the environmental conditions governing variation, would in no way 

 add to our knowledge of the group or aid in its future study. It 

 seems to be the diverging point of a number of species or groups of 

 species, the true relationship of which is at present hard to define. 



OLIVA TIGRINA Lamarck. 



0. tigrina Lam., Ann. du Mus., XVI, p. 322, 1810 (non 

 Meuschen). 



? 0. glandiformis Lam., Ann. du Mus., XVI, p. 317, 1810. 



This species is distinguished from vidua var. macleaya in being 

 less cylindrical in outline with the sutural callus less elevated. The 



