SYSTEMATIC DESCRIPTIONS SPATANGINA. 55 



Museum is the original of Guppy or Cleve is not certain, but it corre- 

 sponds so well with Cotteau's figures that it is probably the Cleve 

 specimen. Somewhat curiously, Cotteau did not feel that he could 

 give a species name to Echinoneus as he described it on page 14 of the 

 work cited, for his published figures are very good. 



The specimen measures 7.5 mm. in height, 17 mm. in length, and 

 12.5 mm. in width. It is interesting to find that this species, which is 

 living at the present time in the West Indian fauna as well as in the 

 Pacific Ocean, should be found fossil in such comparatively ancient 

 geological deposits. It was in this species that Mr. A. Agassiz described 

 (1909, Amer. Jour. Sci., vol. 28, pp.490 to 492, plate 2) the most interest- 

 ing fact that the young of Echinoneus has a lantern, it being at present 

 the only known case of this structure occurring in the spatangoids. 



Oligocene, Anguilla formation, Anguilla, Guppy collection ex Cleve 

 (or possibly from the original Guppy collection), 1 specimen, probably 

 the original of Cotteau's, 1875, plate 1, figs. 28 to 30, U. S. Nat. Mus. 

 No. 115402. Santiago de Cuba, 1 specimen, received January 1910, 

 U. S. Nat. Mus. No. 328223. Cotteau, in his Spanish report, quoting 

 A. Agassiz (Blake Echini), says that this species occurs in the Pliocene 

 of Cuba and Guadeloupe, also the Miocene [Oligocene] of Anguilla. 



Genus AMBLYPYGUS Agassiz, 1846-7. 



Type species. Amblypygus apheles Agassiz, 1847. Cat. Raisonne, 

 Ann. Sci. Nat., ser. 3, vol. 7, p. 166. 



Amblypygus americanus Desor. 



Amblypygus americanus Desor, 1858, Synopsis des Echinides fossiles, p. 256. 



The following is a description of this species: 



Large species, circular in marginal outline, with high rounded border, 

 flattened dome-shaped above, concave below, ambulacra wide, 15 mm. at 

 the ambitus, slightly elevated, non-petaloid, continuous over the border 

 to the peristome. The poriferous areas of the ambulacra are depressed, 4 

 mm. wide at the widest part, which is about midway from the ambitus to 

 the apical disk and from this broadest part narrowing adapically and ado- 

 rally. The apical disk is small, excentric anteriorly. The peristome is a 

 little excentric anteriorly and is small, but the outline is not clear on the 

 plaster cast from which these observations are made. It is, however, doubt- 

 less obliquely elongate, as in other species of the genus. The peristome is 

 evidently smaller than the periproct as noted by Desor. The periproct 

 is large, elongate pyriform, measuring 21 mm. in length and 12 mm. in its 

 greatest width. The peristome is situated on the ventral surface halfway from 

 the peristome to the posterior border of the test. Details of the apical disk, 

 outlines of plates, and tubercles are not distinguishable on the plaster cast. 



The specimen measures 37 mm. in height, 93 mm. in length, and 

 90 mm. in width. 



This species was described by Desor, but has apparently never 

 been figured. He states that the original is in the Michelin collection. 

 The observations here made are based on a plaster cast bearing the 



