438 VARIATION AND ZOOGEOGRAPHY OF LIGUUS IN FLORIDA 



stripes or as spots (fig. 2b, emb., p. 436). On the neanic whorls they may either 

 become interrupted, leaving only spots at the ends (fig. 26) , or they may spread and 

 coalesce laterally producing a pattern of spiral zones or bands. At the periphery 

 the flame pattern is interrupted by a spiral white band, usually bisected by a 

 spiral dark line. There is also a white band below the suture, and in races with 

 normal coloration there is a narrow darker line immediately bordering the 

 suture below. 



The various races of Liguus can mostly be distinguished in the embryonic 

 shells, and the color pattern is characteristically expressed in the early neanic 

 whorls . 



Certain forms seem to be new mutations in the de Vriesian sense. Such are 

 the form solidulus of L. solidus in which the positions of the yellow and white 

 bands are reversed as in a photographic negative. The forms called pictus, 

 testudineus and marmoratus, though independent mutations, are similar in having 

 dark color on areas which should be white in normal patterns. All of these 

 occur in hybrid colonies, and their real gametic constitution probably can only 

 be determined by breeding under control. I have seen no similar forms from 



Cuba. 



V. DISTRIBUTION AND MIGRATIONS OF LIGUUS. 



Liguus is restricted on the mainland of Florida to places on a narrow peripheral 

 strip of firm land, sometimes perhaps six miles wide, frequently much less. In- 

 land this strip is bounded by the everglades in the eastern and southern parts 

 of the peninsula. In the west it is doubtful whether Liguus occurs at the present 

 time on mainland north of Cape Sable. All known localities are insular. 8 Par- 

 allel to this mainland strip in the east and south runs the line of keys, also 

 inhabited by Liguus, but at present isolated from the shore strip. 



On account of the rather extensive though superficial submergence of Florida 

 during the Pliocene and the absence of Liguus from known Pliocene deposits, it 

 is not likely that these snails existed there before the close of the Pliocene, and 

 it seems more likely on geological grounds that their advent was in Pleistocene 

 time. Agassiz and others have pointed out that there has been elevation during 

 the Pleistocene, shown by raised reefs, amounting to over six feet in some places. 

 It is quite likely however that the land area in the peripheral region was as i grra 

 or greater at the period of depression as it is now, since the subsequent eg^ 

 dation must have been much greater on the unconsolidated older area than on ^ 

 newly raised reefs. 9 At all events, it is obvious that the destructive age 



• « 



We kno 



West Coast 



but we did not search it. 



living on the mainland in from Chokoloskee Key " (C. B. Moore). elevation, and 



•According to T. W. Vaughan, Pliocene deposition in Florida was closed by ^ ter wbich t be 



was followed by a Pleistocene submergence. Pleistocene time was closed by an up J» was a s 



t. , , J . , ,„ . -r , ,«..« __ <>* o*x -r# iu Pliocene submergence 



cience 



If the Pleistocene 



as 



must 



This does not appear pro 



ana aajacant mainland must De wnoiiy post-rieisiocene, or nvi^v^. bmerced. 



and Dr. Vaughan does not expressly state that all of the southern region was sud 



