35 



in the middle ; upper margin rather flattened, with a shght concavity 

 at the end of the ambulacra ; under side flat near the margin, deeply 

 concave in the middle ; spines of the under side near mouth very fine. 

 Hab. Australia ; N.S.AV., Brisbane Water. 



2. ECHINANTHUS TESTUDINARIUS. 



Vent beneath a little within the edge, depressed ; back slightly 

 raised, evenly convex ; under surface rather concave from the edge. 

 Hab. Indian Ocean ; Borneo. 



3. ECHINANTHUS OBLONGUS. 



Ovate-oblong, elongate, rounded at the end ; sides thick, rounded; 

 back depressed round the end of the ambulacra ; crown rather convex ; 

 ambulacra ovate, lanceolate, broad, and closed at the end; under 

 side concave nearly to the edge ; ambulacral grooves indistmct ; vent 

 near the margin. 



Hab. Philippines ; Siquijor. 



4. ECHINANTHUS PRODXJCTUS. 



Shell ovate, elongate, the hinder end produced and flattened, the 

 edge rather thick, thinner behind ; the ambulacral petal broad, the 

 bands not quite united at the end ; under side concave to the margin ; 

 vent near the margin. 



Hab. ? 



5. ECHINANTHUS CoLE^E. 



Shell ovate, subpentagonal, depressed; margin thick, rounded ; back 

 depressed as far as the end of the ambulacra, and then rather convex 

 in the middle, the under side concave nearly to the edge ; ambulacral 

 petal ovate lanceolate, closed at the end ; vent near the margin. 



Hab. Mauritius. Lady Mary Cole. 



To those which have a flat base may be added — 



6. ECHINANTHUS EXPLANATUS. 



Depressed, much expanded, centre of the back rather convex ; 

 ambulacra occupying rather more than half the space between the 

 vertex and margin, the lines of pores of the anterior pair and posterior 

 odd one far apart at the end ; cavity with thin concentric lines of 

 short compressed columns near the margin ; iaws depressed 



Hab. Mauritius? o j i • 



Genus Rotula. 



The British Museum series induces me to believe that Rotula digi- 

 tataoi Agassiz is not distinct from R. Rumphii, as M. Agassiz first 

 considered it to be. 



Genus Echinodiscus. 



I cannot find any permanent difference to distinguish Lobophora 

 bifissa from L. aurita ; they are found together in the same habitat 

 in the Red Sea. 



