NO. 6 ECHINOID DISTRIBUTION AND HABITS — KIER, GRANT 53 



vertically one-third length of valve, then angles back to join lower 

 portion of tubular blade; valves in contact distally only at terminal 

 teeth; two terminal teeth of each valve forming horizontal fork; each 

 valve containing internal poison chamber. Small terminal opening 

 between teeth. 



Internal calcareous process. — Support on interambulacrum 4 nar- 

 row, erect, almost vertical, sloping slightly sideways and posteriorly. 



Fig. 15. — Schizaster (Paraster) Eoridiensis. Valve of pedicellaria from 

 figured paratype USNM E10303; X 94. 



Comparison with other species. — This species is easily distinguished 

 from the three living species of the subgenus Schizaster {Paraster). 

 It differs from S. {Paraster) gibberulus (L. Agassiz) from the Red 

 Sea and Indian Ocean in its more anterior apical system, more fiexu- 

 ous anterior petals, narrower ambulacrum III, and lack of transverse 

 ridges in ambulacrum III. It is distinguished from S. {Paraster) com- 

 pact us Koehler from the Bay of Bengal by having the pores in the 

 anterior ambulacrum oblique to each other, a wider higher test, 

 shorter wider posterior petals, and more divergent anterior paired 

 petals. It differs from S. {Paraster) rotundatus Doderlein, a Pacific 

 species, in having a more anterior apical system, its posterior petals 

 not extending as near to the posterior margin, and in having more 

 divergent and more flexuous anterior petals. 



S. {Paraster) fioridiensis is distinguished from the West Indian 

 species Schizaster orbignyanus Agassiz by its more central apical sys- 



