Vol. X] BERRY—SOME UNDESCRIBED CALIFORNIAN HELICES 57 



our Californian snails, the ill-fated Helix anachoreta of W. G. 

 Binney. This is now considered by most authors, no doubt 

 correctly, not to represent a fixed race, but to have been based 

 on a chance light-colored variant such as is known to crop out 

 ephemerally now and then in the race history of many diverse 

 groups of organisms. Hence it has never been shown to inhabit 

 any particular region or station, other than that regularly occu- 

 pied by its "normal" prototype, E. nickliniana (Lea), or its 

 occurrence to be any more than sporadic ; in other words it does 

 not seem to have become hereditarily persistent anywhere. 



With chrysoderma it appears to be quite otherwise. In the 

 first place, this light colored race, so far as the evidence goes, 

 actually does constitute a definite colony in a definite locality 

 and station on the island, as is indicated by "A" in the accom- 

 panying rough sketch received from Mr. Willett, namely among 

 loose talus high on the slopes near the southern end of the 

 island. Typical coronadoensis, I understand, was taken more 

 or less sparingly with it, but proved more abundant on grassy 

 slopes lower down and nearer the end of the island, where 

 chrysoderma failed to recur. In the second place, the differ- 

 ences, though by no means great, appear to be fairly constant 

 within the limits of the considerable series of both forms seen, 

 and not confined to the dilution or lack of periostracal coloring 

 alone. A comparison of the two series brings out the following 

 special peculiarities of chrysoderma, — 1) the very thin, 

 strongly dehiscent periostracum (an exaggeration of a feature 

 already present in some degree in coronadoensis), 2) the 

 notably larger average size*, 3) the light brozvnish-golden 

 color of the periostracum, 4) the lack of spiral color bands of 

 any description, and 5) the more tumid outline of the body 

 whorl. Possibly also the umbilicus averages slightly wider. 

 The animal is light bluish gray in color. 



Although I have recently described a curious little albinistic 

 Vertigo (Berry, :19, p. 48), it was scarcely expected so soon 

 to encounter another instance of an apparently hereditarily 

 fixed albinism in a West American land snail. Very possibly 

 both instances are more properly called albinoids than true 



* The largest of 12 fully matured coronadoensis measures: Maximum diameter 24.1, 

 minimum diameter 20.0, altitude 15.7, diameter of umbilicus 2.1 mm.; whorls S^A. Tbe 

 average values of all the dimensions are: Maximum diameter 22.86, minimum diameter 

 18.95, altitude 14.78, diameter of umbilicus 1.87 mm.; whorls 5.60. 



