- ECHINOIDEA 



645 



M. quinqiuiesperforata (Leske). Keyhole urchin (Fig. 991). Five 

 holes present, 1 interradial and 1 distal to each lateral petal; diameter 

 of test 8 to 12 cm.: Vineyard Sound southwards, in shallow water; rare 

 north of Cape Hatteras. 



3. Encope Agassiz. Test heavy, flat underneath, somewhat arched 

 above, elliptical, truncated behind and with 5 marginal notches or elon- 

 gated holes ; hinder interradial area also with an elongated hole : 6 

 species, littoral; tropical America. 



Fig. 990 



Fig. 991 



Fig. 990 — Echitiarachnius parma, spines removed (Coe). 1, radius; 2, interradius ; 

 3, madreporite; 4, petaloid. Fig. 991 — Mellita quinquiespcrforata (Clark.) 



E. michelini Ag. Margin of test indented opposite the end of the 

 petals (at least the lateral ones), these indentations rarely if ever closed 

 at distal ends so as to form holes; length and width 14 cm. or less: 

 Florida and Gulf coast. 



Order 4. SPATANGOIDA. 



Body secondarily bilaterally symmetrical ; mouth near the forward 

 end of the body and without a dentary apparatus; anus at or near the 

 hinder margin of the body; aboral ambulacral areas petaloid, the for- 

 ward, median area usually differing somewhat from the other four, 

 which are paired, in appearance: about 36 genera and more than 150 

 species grouped in 9 families; tropical and subtropical. 



Family SPATANGIDAE. 



Body more or less heart-shaped; petals well marked: numerous 

 genera and species. 



MoiEA Michelin. Body ovate; apical area behind the middle; am- 

 bulacral grooves deep and slit-like ; mouth far in advance of the middle : 

 3 species. 



M. atropos (Lamarck). Length 5 cm.: North Carolina, southwards; 

 common in shallow water. 



