58 TH. MORTENSEN, (Schwed. Siidpolar-Exp. 



as that figured in i. a, representing part of the abactinal side. The pore-arcs prove 

 this beyond doubt: the figure i. b. shows the rather irregular arcs to have 4 (? 3 or 

 even 2) pairs of pores only, the pore areas narrowing considerably towards the am- 

 bitus; the figure of the abactinal side, 1. a., shows the arcs consisting of 8 pairs of 

 pores close to the ambitus. A comparison with the original specimens shows that 

 the figure of the abactinal side agrees closely with the specimen of HOMBRON and 

 JaquiNOT, whereas the other figure is quite different from either of the two speci- 

 mens. This figure must then be left out of consideration as quite erroneous, be- 

 longing really to quite a different species — I cannot tell which — and only by a 

 mistake put in here as representing the species erythrogrammus. 



Regarding now the type specimen of erytJirogrammns, it really shows a very 

 considerable resemblance to L. albus. The shape of the test, apical system, pores, 

 tuberculation, colour (now very much faded, though showing evident traces of the 

 original colour) are quite the same. The secondary ambulacral tubercles are arranged 

 in two distinct vertical series, as is also the case in some specimens of albus (not 

 in all specimens, cf. the above description, p. 53). 



A comparison with the Australian species commonly called »Strongylocentrolus» 

 {Toxocidaris) erythrogramnuis, gives the result that only one feature seems against 

 that identification, viz. that in the Australian species two ocular plates are broadly 

 in contact with the anal system (as is also seen in the PI. V. a. Fig. 4 of »Revision 

 of Echini^), whereas in the type specimen no ocular plate is in contact with the 

 periproct. Nevertheless, since the South American species is rather variable in re- 

 gard to the ocular plates, there may also be some variation in this point in the 

 Australian species — though I have seen no cases of the ocular pores being shut 

 out from the periproct in that species, and I do not know that such cases have been 

 mentioned in literature. 



The result is then, that it is most probable that the type specimen of Echinus 

 erythrogrammus is identical with Loxechinus albus, but it cannot be said with 

 full certainty. If there had only been a single globiferous pedicellaria left on the 

 type specimen, it would have been easy to decide the question. Under these circum- 

 stances, however, it appears to me that we are not fully justified in making the name 

 erythrogr animus a synonym of L. a/bus, and thus we may keep it for the Australian 

 species, so that no change of name for that species will be needed. — In xRevision 

 of Echini» AGASSIZ gives the Echinus erythrogrammus (pars) as synonym of vStr.* 

 albus, besides as the type of his Strongylocentrotus erythrogrammus (p. 162 — 163). 

 He has thus observed either that the figures or that the original specimens represent 

 two different species; but the reference is not correct, as one of the specimens is de- 

 cidedly Toxocidaris gibbosus, the other either Loxechinus albus or Toxocidaris 

 erythrogrammus, not both of them. 



