2S0 ECHINOSPATAGUS 



Upper Chalk near Norwich, out of the same terrain that yielded Car diaster granulosus, 

 Card, excentricus, and Epiaster yibbus. 



In France it has been collected from the White Chalk at Fecamp, Etretat, and 

 Dieppe, the environs of Beauvais, Meru (Oise) ; of Vervins and La Capelle (Aisne) ; of 

 Andelys, Caussols (Var) ; of St. Julien du Sault (Yonne). 



In Switzerland (according to De Loriol) from the Seewerkalk of Sentis (Appenzell) ; 

 the Grands Troncs near Semsales (Fribourg), Stage Senonien. 



Genus — Echinospatagus, Breynius, 1732. 



Echinospatagus (pars), Breynius, 1732. 

 Spatangus (pars), Klein, 1734. 

 Spatangus (pars), Lamarck, 1816. 

 Toxaster (pars), Agassiz, 1840. 



Body cordiform, more or less inflated at the upper surface, and in general flattened 

 at the base. 



The pairs of ambulacra petaloidal, unequal in length, always large, and lodged in 

 depressions of the test ; poriferous zones wide and slightly unequal in the anterior pair ; 

 pores in the form of narrow slits, those of the outer being longer than those of inner 

 rows ; the anterior poriferous zones are longer than the posterior. The single 

 ambulacrum is lodged in a wide, deep, anteal sulcus, its poriferous zones are narrow and 

 equal with each other, and the holes are smaller and placed closer together than the 

 pores in the pairs. 



The apical disc is compact and solid, composed of four perforated ovarial plates and 

 five small oculars, minutely and finely perforated ; the madreporiform body extends into 

 the centre of the disc. 



The mouth-opening is situated near the anterior border, and the peristome is small 

 and subpentagonal. 



The vent is situated in the upper part of the posterior border, and the periprocte is 

 oval. 



The tubercles, of various sizes, crenulated and scrobiculated, are placed in two or 

 three irregular rows on the plates ; they are most numerous at the anterior border and 

 around the ambitus, and are sparsely scattered on the base ; the surface of the plates is 

 likewise covered with a very fine close-set miliary granulation. 



The absence of fascioles from all parts of the test distinguishes this genus from 

 Hemiaster, with which it has been often confused. The type-species so common in the 

 Neocomian strata of France and Switzerland was first figured by Breynius as Echino- 

 spatagus cordiformis. 



