THE NAUTILUS. 51 



Variety tremulina Lamarck. 



Oliva tremulina Lam., Ann. du Mus., XVI, p. 310, 1810. 



This is well shown by Marrat on plate 8, fig. 1 17. It is in every 

 respect like miniacea except that the aperture is white or bluish 

 white ; fumosa Marr. is only a dark form. The var. pica Lam. 

 (nobilii Reeve 4- concinna Marr.) is more or less coarsely and irreg- 

 ularly marked with dark brown, but forms are before me represent- 

 ing all intermediate stages between tremulina and the var. tenebrosa 

 Marr. in which the dark brown covers the entire shell. 



Variety miniacea (Bolten). 



Porphyria miniacea Bolten, Mus. Boltenianum, p. 33, 1798. 



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



Both authors again refer to the same figures by Martini (Conch. 

 Cab., II, tab. 45, figs. 476, 477). Distinguished from tremulina in 

 having the aperture a bright orange red. Intermediate forms con- 

 nect it with a uniform dark brown form similar to tenebrosa, see 

 Thes. Conch., IV, pi. 7, fig. 109 (var. marrati n. var.). On the 

 other hand the shells become gradually lighter in color and abnorm- 

 ally thickened, representing the var. ponderosa Duclos. The latter 

 seems to be the characteristic form of Mauritius and adjacent islands. 



Variety zeilanica Lamarck. 



Oliva zeilanica Lam., Anim. sans Vert.; VII, p. 436, 1822. 



This represents a smaller race quite readily separated in the adult 

 but completely connected with tremulina in younger specimens. In 

 other words it does not go beyond this juvenile appearance even in 

 the adult. This view is strengthened by the fact that it also shows 

 a parallel variation in color. There is however a variation which is 

 apparently peculiar to this race, which consists of the spire in the 

 adult becoming covered by a callus. Three specimens that would 

 otherwise be typical zeilanica show this feature. This gradually 

 merges into a lighter colored form, often with a violet-colored aper- 

 ture constituting the var. ornata Marr. A light yellow form with 

 only a slight trace of the markings constitutes the var. cryptospira 

 Ford, which merges into a dark brown form resembling tenebrosa, 

 see Thes. Conch., IV, pi. 9, fig. 126 (var. fordi n. var.). These 

 varietal names are given merely for convenience in referring to these 

 extreme forms. 



