TORNATELLIDES. 193 



T. co-nfusa with. 5, to T. terebra with 8 l / 2 . The embryonic- 

 whorls are smooth or faintly sculptured with minute raised 

 spiral lines. The remaining whorls vary from nearly flat to 

 quite convex. It is, however, in the characters of the aperture 

 that the greatest differences are found. The parietal lamella, 

 in adult specimens, may be strong and oblique or it may be 

 present as a weak raised line, which in individual cases is 

 almost absent. In a few species the parietal lamella is irregu- 

 larly eroded in all adult specimens. In the group of T. terebra 

 the outline of this lamella is serrate, with strong, spine-like, 

 outwardly projecting points. In adult specimens, the colu- 

 mella is sometimes unarmed. Usually it is furnished with one 

 or two folds. Immature specimens of a few species have the 

 eolumella furnished with a single oblique thread-like fold, but 

 in most of the species immature specimens have two nearly 

 parallel lamellae on the columella. In some of the species be- 

 longing to the group of T. euryoniphala the lower of these 

 folds is very strongly developed and extends nearly to the 

 middle of the aperture. 



The genus is enormously differentiated and specialized in 

 the Hawaiian Islands, where most of the species have colu- 

 mellar lamella? in the neanic stage, sometimes continuing in 

 the adult. Species from other islands, around the periphery 

 of the Pacific, are more simple, either having no columellar 

 lamellae at any stage, or in the New Zealand species, having a 

 small lower columellar lamella in the young. The few species 

 from, the Japanese Islands, New Zealand, Polynesia and the 

 Galapagos are remarkably similar (see plate 44, all figures). 



Distribution. Fifty-five species of TornatelUdes are now 

 known (three or four of them of doubtful validity), distri- 

 buted as follows : 



Formosa and Japanese Islands, 2 or 3 species (no. 1 to 3). 



Polynesia, Australasia, 3 to 5 species (no. 4 to 8) . 



Galapagos Islands, 1 species (no. 9). 



Hawaiian Islands, 45 species (no. 10 to 54). 



Laysan Island, 1 species (no. 15%) . 



The Polynesian species T. simplex occurs on several island 

 groups, and dispersal by human agency may be suspected. 

 Several Hawaiian species occur on more than one island : 



