6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 145 



is little room for difference of opinion as to what species should be 

 included in this report." In his description of the echinoids of the 

 Barbados-Antigua expedition, Clark (1921, p. 103-104) considered 

 Lytechinus variegatus, Echinometra lucunter, and Clypeaster rosa- 

 ceus as "strictly littoral" and as "those species which occur along 

 shore, or on reefs easily accessible at low tide." 



According to Sharp and Gray (1962, p. 313), Lytechinus variega- 

 tus off North Carolina is most common in shallow water on sandy 

 bottoms where there is material for protective covering and where 

 wave action is at a minimum. They found the small adhesive discs 

 of the tube-feet of this species inadequate for withstanding even 

 moderately heavy wave action. Clark (1933, p. 81) reported that 

 off Puerto Rico L. variegatus is most often found on a rather firm 

 sandy bottom that is covered with short eelgrass or turtle grass. 



I have observed Clypeaster rosaceus and L. variegatus in great 

 numbers off the northeast tip of Key Biscayne, Fla. Here the water 

 is sheltered and less than 3 feet deep. The echinoids live on a sandy 

 grassy floor, and individuals of both species cover themselves with 

 fragments of shells and echinoid tests. Sharp and Gray (op. cit., 

 p. 313) have shown that in L. variegatus this covering of the test 

 serves as a protection against intense light. 



The other two clypeasteroids, Clypeaster subdepressus and Encope 

 michelini, are found in sandy bottoms, but Echinometra lucunter is 

 usually found on rock or coral, suggesting that, although the sea 

 floor was probably predominately sandy, there may have been some 

 areas of hard sea floor. 



The two extinct Caloosahatchee species, the cassiduloid Rhyncho- 

 lampas ayresi and the spatangoid Agassisa porifera, are little help 

 in making paleoecological interpretations. Little is known of the 

 ecology of the cassiduloids (Kier, 1962, p. 21). Rhyncholampas 

 pacificus (A. Agassiz), which resembles R. ayresi, is known from 

 depths of 5 to 60 feet, but nothing is known of its living habits. Of 

 the two living species of Agassisia, one of them, A. scrobiculata 

 Valenciennes, is, according to Mortensen (1951, p. 345), "an emi- 

 nently littoral form," but the other, A. excentrica A. Agassiz, oc- 

 curs in depths from 45 to 900 meters. 



Two of the living littoral species, L. variegatus and Encope 

 michelini, also occur in the Tamiami formation. Four of the extinct 

 Tamiami species, Clypeaster crassus, Clypeaster sunnilandensis, En- 

 cope tamiamiensis, and Mellita aclinensis, are clypeasteroids. Species 

 of this order generally occur in the littoral zone (Hyman, 1955, 



