456 VARIATION AND ZOOGEOGRAPHY OF LIGUUS IN FLORIDA 



above. On the last two whorls the flames become more or less confluent cover* 

 the surface except for curious oval or flask-shaped light spots, a narrow whit ? 

 margin above and below the suture, and on the last whorl there is a light band at 

 the periphery and a small columellar light area, which is yellow in xanthistic 

 shells, violet in those with white ground. 



This form is like the melanistic specimens said to be from Chokoloskee and 

 differs from those of the east coast chiefly in lacking any tendency in the dark 

 flames to split or fork above. Such splitting produces a subsutural tessellation 

 in the Miami race, which is absent in marmoratus. In this Vaca form the 

 melanistic mutation has been superposed upon a slightly larger, longer race 

 than at Miami. A specimen of marmoratus has been figured by W. G. Binney, 

 4th Supplement to Terr. Moll. V, pi. I, fig. 5. It was collected by Hemphill 

 on Key Vaca in 1883. Nine of the shells from Key Vaca measure: 



Length 54, diam. 27, aperture 25 mm. (apex truncate). 



Length 56.5, diam. 26.5, aperture 25.5 mm. (apex truncate). 



Length 50, diam. 26, aperture 23.5 mm. 



Length 57, diam. 26, aperture 23 mm. 



Length 46, diam. 21.5, aperture 20 mm. 



Length 53, diam. 25, aperture 24 mm. (xanthistic). 



Length 58, diam. 26.5, aperture 25 mm. (marmoratus). 



Length 53, diam. 24.5, aperture 22.5 mm. (marmoratus). 



Length 45, diam. 24, aperture 21.5 mm. (marmoratus). 



In the blackest examples, as fig. 9, the green lineation of crenatus is represented 

 by obscure lines visible only in certain lights. 



This marmoratus form is parallel to but not in any way directly connected 



with the East Coast tortoise-shell form (testudineus) . 



5. Hybrid Colontes composed of 



X ROSEATUS X 



ZONATUS, AND SEGREGATING INTO THREE OR FOUR PATTERNS. 



On the west side of Biscayne Bay, south of the Miami River, the colonies of 

 Liguus are heterogeneous, consisting of the forms crenatus, roseatus, castaneo- 



zonatus and testudineus or " mosaics.' ' , , . 



It was the experience of Mr. Rhoads, Mr. Moore, and myself that the darKesi 

 forms are to be found only in the most dense and shady hammocks; where also 

 richest yellows occur. The paler races are found copiously with ^ em, ^ e J n " 

 where the most abundant form ; but they have also a wider range in : more P 

 and therefore lighter woodland. The significance of this selective .?° 00 ds 

 is not clear. It may be that the food-fungus in the more shaded, humid 

 affects the amount of dark pigment deposited in the shell. has 



1. Plate XXXIX, figs. 20 m, n, o. The most abundant form, crenaw ,^ 

 a ground of either white throughout, or deep yellow on the last wnor 



