This morph is typical of an extensive scries of local races 

 found over a considerable area in the San Juan group, the 

 shores of the mainland bordering on Rosario Strait, and parts 

 of Puget Sound. The spire is moderately produced and the 

 spiral sculpture is reduced to a single low ridge, while the ver- 

 tical lamellae are nearly or quite obsolete. The coloration in 

 this morph forms a pattern which is common to an immense 

 number of local races, quite independent of morphological 

 features. We find some individuals in which color is entirely 

 lacking, while at the opposite extreme we have those with a 

 uniform brown coloration. Between these we have a graded 

 series of banded forms connecting the extremes, and thus 

 forming what might be regarded as clines within the local races. 

 Illustrations of this phenomenon will be seen in widely sepa- 

 rated populations, as in morphs 12, i8, 22, 30, 37, etc. 



This condition finds a ready explanation from the stand- 

 point of genetics. 

 Specimens available, 100. 



Morph 12. Plate xxvii. 



Fidalgo Island, although it is so termed, has rather the char- 

 acter of a peninsula separating Rosario Strait from Padilla 

 Bay, since it is separated from the mainland by a narrow 

 slough. 



The shoreline of Fidalgo includes several rocky capes, each 

 of which bears a related but distinctive population of Tbais. 

 The morph illustrated was derived from Shannon Point which 

 extends from the northwest border of the island. It is intro- 

 duced partly to indicate that even in widely separated areas 

 phenotypcs of very similar appearance may be developed. 

 Specimens available, 100. 



Morph 13. Plate xxviii. 



Port San Juan, otherwise known as Port Renfrew, is an in- 

 dentation in the southwestern coastline of Vancouver Island. 

 The Thais population of this area proved to be extremely 

 varied, the shells differing not only in the coloration but also 

 in sculpture and spire form, making it difficult to adequately 

 represent the lines of variation within the limits of a single page. 



