Btl. VI: 4) THE ECHINOIDEA. 41 



The specimens from Stat. 2 (off the La Plata) correspond to the var. Hassleri 

 of DODERLEIN in being somewhat lighter in colour than the typical form. The 

 spines are a little longer than is generally the case in the typical specimens, but, 

 as seen from the measurements, they may be quite as long in the typical form. 

 Regarding the number of the coronal plates, which is mentioned by DODER- 

 LEIN as the most important character, the variety having somewhat fewer plates 

 than the typical form, the enumerations given above show that in these specimens 

 at least, there is no such constant difference. On the other hand I find the test in 

 these specimens generally distinctly pentagonal, whereas in the typical form it is 

 generally quite round. Upon the whole I think it scarcely possible to maintain this 

 form as a distinct variety; it is probably only a slightly modified deep-water form. 

 (The station 2 is near the locality of type specimens of the Var. Hassleri.) 



As will be remarked from the list of synonyms given under this species, I 

 think it not improbable that Notech. magellanicus is really the same species as the 

 Echinus margaritaceus Lamk. figured by VALENCIENNES in the Atlas of the »Venus» 

 (Zoophytes PI. 6. Fig. 1). Since, however, this can no longer be determined with 

 certainty, the specimen having been lost, the name magellanicus will have to be 

 kept. As for the species called margaritaceus by AGASSIZ and DODERLEIN, it is 

 certainly not identical with Lamarck's species, but this is treated more fully under 

 Ster echinus Agassizii (p. 43). 



It is with full right that DODERLEIN has removed this species from the genus 

 Ster echinus, to which genus I had referred it in the Ingolf Echinoidea I. Un- 

 doubtedly the genus Sterechinus thus becomes much more natural and well limited. 

 That magellanicus agrees in several respects with Pseudechinus albocinctus I had 

 perfectly realized (Op. cit. p. 106), but especially De LORIOL emphasizes the cor- 

 respondence between these two species. It must be agreed that one might indeed 

 be tempted to refer them to one and the same genus. After all I must, however, 

 join DODERLEIN in making magellanicus the type of a separate genus, mainly on 

 account of the globiferous pedicellarias, which have in albocinctus only one lateral 

 tooth, as in the family Echinometridae. Besides, the curved actinal spines and the 

 two kinds of globiferous pedicellariae in magellanicus are rather conspicuous diffe- 

 rences from albocinctus (I have been unable to find more than one form of globi- 

 ferous pedicellariai in albocinctus, having carefully examined the several specimens 

 at my disposal); on the other hand, the fact that in albocinctus the globiferous pedi- 

 cellariae have double glands as in magellanicus is noteworthy. It seems, indeed, that 

 the two species: magellanicus and albocinctus show the way from the Echinidae to 

 the Echinometridae. — In case it be ultimately proved that these two species cannot 

 be referred to different genera — or even different families — magellanicus must be 

 referred to the genus Pseudechinus, to which Notechinus will then be a synonym. 



6 — 100133. Schwedische Siidpolar- Expedition iqoi — iqoj. 



