6 PLEIOCENE FOSSILS. 



belts and the obliteration of the anterior half-ambulacrum in each member of the forward 

 pair. 



Plate I., Fig. 5. Upper surface. 

 " 5a. Profile. 

 " 5b. Lower surface. 

 Plate II., Fig. i. Enlarged view of part of an ambulacrum of the forward pair, showing the minute 

 pores of the obsolete half-row. 

 ia. Magnified view of a large tubercle from beside the odd-ambulacrum. 



Locality. The Grove, Cooper River, S. C. (J. McC.) 



AMPHIDETUS. — Agassiz. 



AMPHIDETUS AMPLIFLOKUS.— McCkady.— (New species.) 



Plate II., Fig. 2. 



Amphidetus maximus cordiformis modici longus, A. gothico longior ; anteriorem testam la- 

 tissimus ; A. orthonoto aliquantulum similis sed antice angustior, et posteriora latera non 

 compressus y gibbo anteriore vix prominente, et posteriore quoque liumilissimo ; fasciolae in- 

 ternae area latissima antice angustior e, et magnis tuber cutis clavata / fasciolae subanalis non 

 conservata, Stella ambulacrali ampla, poris rotundatis, et intra fasciolam intemam apertis 

 poris paucis et ad apicem sexualem non pertingentibus • apice sexuali mediano ; foraminibus 

 genitalibus appropinquatis / inter ambulacr or um parium posteriorum jugis descendentibus re- 

 motis • facie anali non conservata, verum probabile est, quam A. orthonoti angustior e, plus 

 rotundata etplus verticali. 



Description. A large species, heart-shaped and at first sight similar to A. orthonotus, 

 (Plate II., Fig. 1, la, lb, lc,) but differing in being not quite so broad anteriorly and narrow- 

 ing less suddenly towards the Anal Facet ; not very long, but longer than A. gothious, next 

 to be described. The anterior hump is rounded off, and much less prominent than in A. 

 orthonotus ; the posterior inter-ambulacral hump being almost nothing. The field of the 

 inner star-belt is very broad, but narrowing towards the front, while the knops which stud 

 it are of large size. The ambulacral star is ampler, covering more of the upper surface than 

 in the Virginian species ; its pores are more or less rounded and the rows of open pores 

 within the belt do not reach the sexual centre, which is median ; the genital openings are 



