4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I45 



because so many of the species are confined to the Tamiami or found 

 elsewhere in poorly dated beds. Five of the species are confined to 

 the Tamiami; two of the subspecies to the Tamiami and Caloosa- 

 hatchee. Clyp easier crassus Kier, new species, has been found in 

 South Carolina in deposits considered by Cooke (1959, p. 36) to be 

 Pleistocene, but Wilson (1962 personal communication) suggests 

 that these deposits may be Late Miocene. 



EVOLUTION 



Many of the taxa in the two formations and those living today 

 in the Caribbean are so similar that it is reasonable to suggest sev- 

 eral phylogenetic lineages (fig. 1). Clypeaster subdepressus, a species 

 known from the Caloosahatchee and the Recent, appears to be de- 

 scended from the Tamiami Clypeaster sunnilandensis. The two 

 species are alike in all characters except petal III, which is open in 

 C. sunnilandensis and closed in C. subdepressus. Clypeaster rosaceus 

 dalli is distinguished from Clypeaster rosaceus rosaceus only by its 

 broader test. Clypeaster prostratus, a living species, can be dis- 

 tinguished from the Tamiami Clypeaster crassus only by its thinner 

 margin ; it is probably descended from it. 



Encope michelini imperforata from the Tamiami and Caloosa- 

 hatchee is probably the ancestor of Encope michelini michelini, known 

 only from the Pleistocene-Recent. The two subspecies are very simi- 

 lar, differing only in the development of the posterior 1 untile. Ly- 

 techinus variegatus plurituberculatus, also from the Tamiami and 

 Caloosahatchee, is similar in all respects to Lytechinus variegatus 

 variegatus except for the number of tubercles in the ambulacra. 

 Rhyncholampas ayresi from the Caloosahatchee is similar to Rhyn- 

 cholampas evergladensis from the Tamiami and probably is descended 

 from it. 



ECOLOGY 



Echinoids of both the Tamiami and Caloosahatchee formations 

 evidently lived in shallow water. Five out of the seven species found 

 in the Caloosahatchee formation are still living: Lytechinus varie- 

 gatus, Echinometra lucunter, Clypeaster rosaceus, Clypeaster subde- 

 pressus, and Encope michelini. These species occur today in shallow 

 water. H. L. Clark (1933) included all of them in his report on the 

 littoral echinoderms of Puerto Rico. According to Clark (op. cit., 

 p. 74), "the littoral sea urchins are so well known and the line be- 

 tween them and the deep water forms is so easy to draw that there 



