408 s. Goix) : 



difference araoug the various ALiskau examples tlian exists between these 

 on the one hand and either the Noi-wegian or Rliode Island specimens on 

 the other. Tlie width of the pxxillar area on the arm varies in this species, 

 even in specimens from the same locality. It is not sm-prising, therefore, 

 that the area is narrower in the specimens from Norway, just mentioned, 

 than in the figiue of Duben and Koren.'^ Düben and Koken figure also 

 the superomarginal plates and paxillae, the iuferomarginals and adambula- 

 oral plates, and fortunately the tube-feet. These liave strong sucking disks. 

 Tlie figure is enough to place the animal in Pseudarchaster. 



" That Astropecfeu parelii and Pseudarchaster intermedim are one and 

 the same (somewhat variable) species I have not the slightest doubt. I also 

 doubt if Pseudarchaster faUax is auytliing more than a variety. 



" Sladen placed j^'^^'^^cUi in Tcthyaster, a subgenus of Phitonaster, wliile 

 Bell, Norman, Greeg, and Ludwig relegated it to Phitonaster. Such a 

 com'se is untenable, because Phitonaster belongs to a different family altogether, 

 and has pointed tube feet, never sucking disks. This character alone 

 is enough to exclude parelii from Phitonaster. As a matter of fact, p:irelii is 

 so near the type of Pseudarchaster [that is, discus'] that one is obliged 

 to search carefully to find trencliant difierences. The following are the 

 considerations which lead one to rank parelii in Pseudarcliaster : tube feet 

 with sucking disks ; character of the marginal plates, especially the iufero- 

 marginals ; the characteristic adambulacral plates and armature, which is 

 totally unlike Phitonaster ; the actiual intermediate plates with spaced 

 gi'anules and incipient central spiuule ; the armatm-e of the mouth plates, 

 there being an unpaired median tooth directed over the actinostome ; the 

 presence of postadambulacral fascioles veiy characteristic of Pseudarchaster 

 and never found in Phitonaster or allied genera. 



"In a specimen oi parelii from the Copenliagen Museum: 11 = 43 mm., 

 r = 14mm. ; superomarginals twenty-tlu-ee ; the superomarginals are consi- 

 derably arched alx>ve the abactinal paxiUar area on arms ; the latter is 

 narrower tlian the marginal plates, there being at the middle of ray only 



1) " Plate 7, fig. 4." 



