NO. 5 TERTIARY ECHINOIDS FROM FLORIDA — KIER 41 



Shape. — Smallest specimen 16.5 mm long, largest 73 mm (see 

 table 3 for dimensions) ; margin subcircular except for truncated 

 posterior margin on some specimens; width approximately equal to 

 length; test very low with thin sharp margin; adoral surface flat 

 to slightly concave ; 5 elongate ambulacral lunules in large specimens, 

 lunule in ambulacrum III smaller than others; lunule in posterior 

 interambulacrum very elongate, extending far between petals. 



Apical system. — Slightly anterior, distance from anterior margin 

 to apical system approximately 45 percent of length of test; large 

 madreporite ; four genital pores. 



Table 3. — Dimensions of 11 specimens of Mellita aclinensis Kier, neiv species 











Length of petal 





-ength 



Width 



Height 



III 



II 



I 



mm 



mm 



mm 



mm 



mm 



mm 



16.5 



16.3 



2.4 



4.0 



3.8 



4.3 



21.8 



22.5 



2.7 





4.4 



6.1 



22.7 



23.0 



3.1 



5.7 



5.0 



6.3 



24.0 



23.6 



3.2 



5.9 



5.4 



6.4 



25.7 



25.5 



3.3 



6.0 



5.5 



. . . 



30.0 



32.7 



4.0 



7.9 



7.4 



9.1 



31.7 



31.4 



4.1 



8.5 



8.3 



8.9 



35.0 



37.0 



5.0 



9.2 



7.7 



9.8 



44.0 







10.5 



10.0 



12.1 





56.0 



5.6 



11.2 



11.3 



15.3 



73.0 ... ... 



Ambulacra. — Anterior petals II, III, IV lanceolate, straight, 

 petal III longer, extending almost two-thirds distance from apical 

 system to anterior margin, petals II and IV only halfway to margin ; 

 posterior petals V and I longer than anterior petals, not straight but 

 curving posteriorly; in all petals poriferous zone equal in width to 

 interporiferous; petals almost closed; in specimen 35 mm long, 34 

 pore pairs in single poriferous zone of petals II, III, IV, 47 in petals 

 V or I. Adorally, five pairs of food grooves extending from peri- 

 stome to near margin (pi. 15, fig. 3) ; area circumscribed by pair 

 of grooves expanding distally with greatest width near lunule, con- 

 stricted distal to lunule ; area broad between adjacent pairs of grooves. 

 Secondary pores difficult to see in most specimens, apparently con- 

 fined to area circumscribed by food grooves. 



Periproct. — Opening small, elongate, located at anterior edge of 

 lunule. 



Peristome. — Anterior, small, subcircular to pentagonal, food 

 grooves bifurcating near peristome. 



