63 



In this population we find little variation in size or spire 

 form, but a graded series as regards sculpture, both spiral and 

 vertical bands varying from a sharply defined expression to 

 forms in which both sets of bands are almost obliterated, thus 

 forming a clinal system. The coloration is absent or obscurely 

 indicated. 

 Specimens available, 25. 



Morph 37. Plate Lii. 



Jessie Island is located in Departure Bay, British Columbia. 

 In this morph there is present the elongated spire and balanced 

 development of the spiral and vertical bands which are char- 

 acteristic of many northern populations. The coloration of 

 the shells follows the pattern so frequently noted of a graded 

 series, ranging from pure white to dark chocolate. The sculp- 

 ture also exhibits the graded pattern so commonly met with. 

 Specimens available, 100. 



Morph 38. Plate liii. 



McLean's Arm is an indentation in the southeast coast of 

 Prince of Wales Island in Alaska. In this morph the shell 

 form is of the type common to many populations in British 

 Columbia and Southeastern Alaska, with elongated spires and 

 balanced sculptural pattern. In this instance coloration is al- 

 most completely lacking. 



Morph 39. Plate liv. ^ 



Thumb Bay is an indentation in the coastline of Knight 

 Island, Prince William Sound, Alaska. This morph is notable 

 for the extreme length of the spire in the majority of the 

 specimens, and the tendency of some of the variants to develop 

 close-set imbrications. The coloration is of the common type, 

 with a graded series ranging from brown to white. 

 Specimens available, 50. 



Morph 40. Plate Lv. 



Washington Bay is an indentation in the coastline of Kuiu 

 Island, in Southeastern Alaska. 



