324 LAMINELLA. 



it part of the species to form their new group Amastra. The 

 lists of species given by von Martens, Adams and Pease show 

 that their views of the groups dealt with were hazy, in con- 

 trast with Pfeiffer's clear vision. Von Martens placed the 

 yellow Laminellas in Newcombia, his Laminella being com- 

 posed of L. gravida and most of the Amastra; other Amastra 

 he included in Leptachatina. Pease was the first to give 

 Laminella generic rank. Sykes has herded several sinistral 

 Amastrae among his Laminellae ; but Baldwin, in his Catalogue 

 of 1893, eliminated all Amastroid forms, limiting the group 

 exactly as in the present work. 



ORIGIN. The ancestral stock of Laminella probably had 

 shells marked with oblique or angulated dark lines or stripes 

 on a yellow or pale ground. This inference rests upon the 

 fact that the pattern is 'common to almost every species, if 

 not in the adult, then on the early neanic or last embryonic 

 whorls. The exceptions are a few species or individuals in 

 which no pattern is developed. Part of the Amastrae of Molo- 

 kai, Maui and Lanai have a similar pattern. They probably 

 descended from the same Amastrella stock, though a tendency 

 to zebra-striping in various totally diverse Achatinellid 

 groups of Molokai-Maui must be conceded. Certain of the 

 angular-striped Amastrae (the biplicata group) have a simi- 

 lar tendency to duplicate the columellar fold. Whether the 

 color-pattern and columellar structure were expressed in the 

 common ancestors of Laminella and Amastra is somewhat 

 doubtful. They may have been developed orthogenetically. 

 Cf. also Partulvna, Newcombia and Perdicella. 



The theory that Laminella had its origin in the Molokai- 

 Maui-Lanai area has its basis in two facts: In this area the 

 genus has many diversified species, while in Oahu there are 

 but three species, these belonging to one of the Molokai- 

 Maui-Lanai groups. In the eastern islands Laminella has its 

 very characteristic color-pattern in common with Amastrae 

 special to the same islands, suggesting the inference of a com- 

 mon ancestry, while in Oahu the Laminella species stand con- 

 spicuously apart from all other snails of the island. 



COLOR-PATTERNS. The color-pattern in Laminella is usu- 



