KCHINOIDEA. I. 135 



Species: Ecli. cscnlfntiis L., acutus Laink., mclo Laink., clegans Diib. Kor., gracilis Ag., Alex- 

 andri Dan. Kor., lucid us Doderl., a/finis n. sp., atlantic^is n. sp. 



Distribution: The Atlantic Ocean, the Mediterranean, the Pacific Ocean. Littoral-archiben- 

 thal forms. 



Sterechinus Koehler (emend.). 



Pores trigeminate; primary tubercle on every or only on every other ambulacral plate. 

 The buccal membrane most frequently with numerous fenestrated plates inside of the buccal plates, 

 outside of these it is almost or quite naked. Generally one or more (all) of the ocular plates reach to 

 the periproct. The secondary spines often fine, silky; the actinal primary spines curved at the point 

 (always?). The globiferous pedicellariae generally with the edges connected across the inside of the 

 blade. The tridentate pedicellarise broad, leaf-shaped; the edge not thickened, only with a single 

 series of teeth. 



Species: Stcrcch. margaritaceus (Lamk.), horridiis (Ag.), Neumayeri (Meissn.), magellanicus (Phil.). 



Distribution: The southern and western coasts of South America, the Antartic Seas. Littoral- 

 archibenthal forms. 



Paracentrotus n. g. 



Pores multigeminate. Primary tubercle on all the ambulacral plates. The buccal membrane 

 with fenestrated plates both inside and outside of the buccal plates (outside, however, rather few). 

 None or i 2 ocular plates reach to the periproct. The spines long and rather thick; the actinal ones 

 not curved at the point. In the globiferous pedicellariae the edges are not connected by cross-beams 

 across the inside of the blade. The tridentate pedicellarise long, narrow, without transverse series of 

 small teeth. 



Species: Paraccntr. lividus (Lamk.), Gaiuiardi (Blainv.). 



Distribution: The Mediterranean and the adjoining Atlantic coasts. Brazil. Littoral forms. 



Fam. Toxopneustidae Troschel (emend). 



The globiferous pedicellariae with end-tooth, but without lateral teeth; the edges of the blade 

 quite coalesced on the inside, so that the blade is tubular. Peculiar dumb-bell-shaped or somewhat 

 branched spicules are generally found in the globiferous pedicellariae and often also in the tube feet; 

 bihamate spicules are generally also found ; in one form (Strongylocentrotus pulcherrimus) only biha- 

 mate spicules are known. Generally i 2 ocular plates reach the periproct. 



Subfam. Schizechininae Pomel (emend). 



The spicules in the globiferous pedicellariae dumb-bell-shaped or small bows not pointed at the 

 ends. Generally deep slits in the test. The globiferous pedicellariae without neck; mostly with glands 

 on the stalk. The stalk compact. 



Genera: Psam-mcchinus, Gyiiui<-chiims, Toxopneustcs, Tripncustes, Sphcercchinus, Pseudobolctia, 

 Pseudoccntrottis. 



