170 Papers from the Marine Biological Laboratory at Tortugas. 



Murex rufus Lam. Erato maugerias Gray. 



Sistrumsp., recent on Florida east coast. Trivia quadripunctata Gray. 



Engina turbinella Kiener ? x Omphalius fasciatus Born. 



Colunibella pulchella Kiener. Fissurella alternata Say. 



mercatoria Lam. Area gradata Broderip. 



Colubraria lanceolata Menke. Lticina radiata Conrad. 



Strombus, young, probably pugilis Linn. Chione cancellata Linn. 



All of the identifiable forms perhaps excepting three (those indicated by an 

 ■"x") are recent. On a percentage basis 90 per cent are surely recent. The horizon is 

 therefore probably old Pleistocene, probably somewhat older than the Miami oolite. 



This list will be referred to subsequently. 



The prevalence of coquina on the east coast indicates shallow-water 

 beach conditions, with alternations of accumulations of sands and wave- 

 ground shells. 



Dall says concerning the west coast: 



There is general opinion among the inhabitants, which was frequently ex- 

 pressed to me in conversation, to the effect that between Tampa and the keys 

 Coquina-rock is only to be found at one place, the mouth of Little Sarasota Bay. 

 But this idea is certainly erroneous, as at every projecting point of the keys along 

 the Gulf shore which we visited, I found traces of this rock, though often not visible 

 above water, and frequently composed more of sand grains than of shell, so that 

 it looks much like wet loaf sugar. (Amer. Jour. Sci., 3d ser., vol. xxxiv, pp. 162, 

 163, 1887.) 



SHELL MARL. 



This material is composed mostly of the tests of mollusks, embedded 

 in a matrix of quartz sand with a varying proportion of amorphous and 

 fragmental calcium carbonate. It occupies a very large area extending 

 south and southwest from Daytona from the northern margin of the 

 Pleistocene sea at least as far as the northern margin of Lake Okeechobee, 

 on both its east and west sides. It probably extends as far as the south- 

 ern end of the Lake on its east side; and certainly does on the west, 

 where there are excellent exposures on Caloosahatchee River. 



The fossils listed from the well at Delray represent a shell marl, 

 and give evidence of the southward extension of this class of material 

 along the east coast. 



West of Fort Lauderdale, along the southern drainage ditch, there 

 is evidence of intergradation of shell marls and the Miami oolite. First 

 Shaler ' and later Griswold - have called attention to the contemporaneity 

 of coquina and the oolite. The same may be said of the shell marls. 



The collections of fossils from the shell marls, made by Dall and 

 Willcox, later by Matson, Clapp, and myself, have given a fair knowledge 

 of the paleontology of these Pleistocene deposits. Dall has pubHshed 

 a Hst of the species obtained from North Creek, near Osprey. Manatee 

 County,^ and Matson and Clapp have published lists, based on my identi- 

 fications, of the species from a number of localities. They, however, 

 omitted two important lists, and I insert them in this paper: 



1 Mus. Comp. Zool., Bull., vol. xvi, p. 143, 1890. 



^ Mus. Comp. Zool., Bull., vol. xxviii, pp. 55, 56, 1896. 



^Wagner Free Inst. Sci., Trans., vol. iii, pt. vi, pp. 1616, 1617, 1903. 



