358 PARTULINA. 



variable in the series examined. The pattern of longitudinal 

 zigzag stripes is distinct in places, or the stripes have been 

 so dislocated that usually a mottled effect is produced. In 

 both color and shape it has some resemblance to P. grisea Nc., 

 which differs by being sinistral, larger, with a different pat- 

 tern of color on the embryonic whorls, and a less prominent 

 columellar fold. P. carinella has much the same general color, 

 and no doubt is somewhat related. 



Named for the Rev. E. W. Thwing, whose compilation of 

 the original descriptions of Achatinellidtz has been a useful 

 handbook for Hawaiian conchologists. The large collection 

 made by Mr. Thwing now belongs to the Bishop Museum. 



PAETULINA CARINELLA (Baldwin). Page 7. 



This species is undoubtedly a Perdicella, as Dr. Cooke and 

 Mr. Thaanum have pointed out to me. It should be removed 

 from Newcombia, which without it consists wholly of sinistral 

 species. 



Section PARTULINA. 

 PARTULINA VIRGULATA (Migh.). Page 25. 



This species inhabits the eastern part of Molokai, almost 

 one-third of the island 's length ; from Pelekunu and the first 

 valley northwest of Kamalo to the eastern end of the island. 

 Mr. Thaanum, who has had wide experience with the species, 

 finds that eastward of Waialua individuals are sinistral in 

 great majority. Out of 1,067 collected by him, 1,053 are sinis- 

 tral, 14 dextral. West of Waialua the banded (typical) form 

 is almost always dextral, while the plain or faintly banded 

 form (pi. 26, figs. 1, la, Mapulehu, coll. by Thaanum) is sin- 

 istral, though both may be found on the same tree. The 

 factors for plain coloring and sinistral coil are evidently 

 linked in inheritance. 



In the first valley west of the heads of Kamalo, just above 

 the irrigation ditch, east of the stream, the authors found a 

 small, well-banded form of virgulata about 21 mm. long. This 

 is probably the extreme western limit. Typical banded vir- 

 gulata was taken by Thaanum in Honouliwai, a place far east- 

 ward, not before recorded. 



