ECHINOIDEA. I. 



167 



12. Onh' everv other interainbulacrril plate above the ambitus 

 with a primary tubercle; the primary spines rather short, 



greenish ; the form of the test almost globular Echinus iiie.lo Lamk. 



Only a few interambulacral plates nearest to the ajjical 

 area want primary tubercle; the primary spines most fre- 

 quently rather long, reddish; the test high or more or less flat Ec/iiuiis anti/ts') Lamk. 



13. The spicnles branched in the ends, none dumb-bell-shaped; 

 the globiferous pedicellaria; with long, muscular neck; no 



glands on the stalk. The pores niultigeminate Strniigyloccntrohts drohacliicnsis (Miill.i 



The spicules of the pedicellarite dumb-bell-shaped, those 

 of the tube feet branched in the ends; the globiferous 

 pedicellarife without neck, with glands on the stalk. The 

 pores niultigeminate SphcBrccJiiims granularis^) (Lamk.). 



Several results of importance to the study of the geographical distribution will appear from 

 the present researches. A complete representation of these results must, however, be delayed, till the 

 irregular Echinids have been treated. Here I shall onl\- briefh- mention one feature of greater interest, 

 viz. the resemblance between the arctic-subarctic and the antarctic-subantarctic Echinid-fauna, as this 

 resemblance is chiefly based on the regular Echinids. 



Meissner (285) gives a comparison of the Echinid-fauna of the two regions after the state- 

 ments in the literature: one species occurs in both these regions, is bipolar , \iz. Echinus norvegictis. 

 The following .species represent each other: Cidaris canalicnlata and papilla fa. Echinus inagellanicus 

 and iiiiliaris, E. niargaritaccus and rlcgans^ Strong\loccntrotns albus and Jriibachirnsis^ Schisasier Phi- 

 iippii a.n^ fragilis. I shall express no opinion with regard to the two ^V/z/cc/jAv-species , but all the 

 other points of resemblance between the two faunas are quite illusor\'. I have shown above that 

 Echinus norvegicus is not bipolar. The statement originates from Agassiz (Challenger; Echinoidea 

 p. 117), but is wrong. The specimens (from st. 308) that have been referred to Ech. norvegicus, are 

 partly Stercchinus inagellanicus, partly an Echinus-S'pec\es that has nothing to do with >wrvegicus\ it 

 belongs to the species with primar\- tubercle on all the ambulacral plates; it is perhaps a new species. 

 — i<Cidarisi canalicnlata and papillata can in no way be said to correspond to each other, they belong 

 to two different genera, Stcrcocidaris and Dorocidaris; any two other Cidarids might as justly be said 

 to represent each other. Echinus inagellanicus and iiiiliaris, to be sure, are rather similar with 

 regard to habitus, but as they belong, not onl\- to two different genera, but to two different sub- 



■| With regard to var. tiwdilcrranea, Flenn)igii, and norvegicus I must refer to tlie description above (pp. 154—155). 

 -) I cannot give the characters of Sphcerechinus roseus more particularly, as I have not seen this species; the reader 

 is referred to Russo's description of it (347). 



