HYATT'S CLASSIFICATION, ETC. W57 



modified form in the Kaala range, it follows also that the 

 directions of these migrations was finally turned towards 

 the west. That the gravida may have been artificially trans- 

 ported to the western range must also be admitted, so long 

 as the evidence remains as it is at present, because any na- 

 tural transit across the valley of the Ewa district would be 

 impossible from a point so far south. Luckily the arrange- 

 ment of the second section, which comprises all shells found 

 to the eastward of Oahu, does not present the difficulties just 

 noticed in tracing the genealogy of L. sanguinea. 



It is comparatively easy starting with L. venusta of Molo- 

 kai to trace this by gradations into L. depicta, and this in 

 turn into helvina and citrina. There is also a lateral off- 

 shoot from venusta in L. alexandri. In whichever direction 

 one looks at related forms, whether to the west or the east 

 of Molokai, it is obvious that this fauna, so far as Laminella 

 is concerned, is retrogressive in size. That it is not retro- 

 gressive in the pattern of coloration is shown by the evident 

 relationship of the highly colored and complex pattern of 

 sanguinea on Oahu to the simpler gravida. 



In passing from the dwarfs of Molokai to the larger shells 

 of West Maui, strong evidence of direct -connection between 

 venusta of Molokai and picta of the last locality is shown in 

 all the characters of all the species, including their develop- 

 ment, and it is evident also that the latter is the progressive 

 descendant form, if the migrations of the species took the 

 same direction as those of other genera. The evidence with 

 regard to this is not as complete as is desirable, but it is cer- 

 tainly easier to account for the generation of the different 

 island faunas of Laminella by assuming an easterly set from 

 island to island of the tide of migration, starting with Oahu, 

 than to start with Lanai and end in Oahu. In West Maui 

 L. picta leads into L. bulbosa of East Maui, and connects 

 more nearly with L. tetrao of Lanai than the latter. This 

 accords with the geographic approximation of W. Maui to 

 Lanai, and the connection of the fauna in other genera. 



