PLATE CLXXV. 



ECHINUS Pentaphorus : orbiculata depressa, foraminibus quin- 

 que oblongis ; ano ori proximo. 



Echinus pentaphorus ambulacris apice emarginatis, ano ori proximo : 

 foraminibus quinque. Leske apud plein echinod. 

 p. 1.97. — Gmel. Syst Nat. T.l. p. 6. 8189. 65. 



Scutella Quinquefora, Scutelle a cinq trous. Lamarck An. 

 sans Vert. t. 3. p. 9. 4. 



This curious species of the depressed or flat kind of the Echinus 

 tribe bears such a near approximation to the species heocaphorus, or 

 six-holed Echinus, that some naturalists have conceived they are 

 both of the same species, differing only in this particular. 



We are not, however, entirely assured of the accuracy of this 

 opinion ; we have both kinds now before us, and have some hesitation 

 in acceding to that opinion . Echinus Pentaphorus is smaller, and 

 our specimens of the latter is of a more rounded form than the 

 other ; we have indeed seen the same kind more dilated across the 

 middle, and consequently the circular figure of its contour is not so 

 constant as to form a positive character. The species distinguished 

 by having six perforations is known to be a native of the Indian and 

 American seas; the habitat of that with five perforations is yet 

 doubtful, although it is believed to be the same as that of the 

 preceding. 



