GENERA AKD GROUPS OE THE ECHIISTOIDEA , 219 



Subgenus Macrastee, J^. Boemer (genus), 1888, JVeues Jahrh. f. 

 Min. It. Geol. Bd. i. p. 191, pi. vi. 

 Peristome without a projecting labrum. 

 Fossil. Cretaceous : Texas, N". America. 



Breynius certainly placed several species belonging to very 

 different genera in his Echinospatagus ; but Agassiz in 1840 

 failed to produce a homogeneous group in Toxaster, which he 

 considered to be a good genus and to supersede that of Breynius. 

 Since the date of the Catal. Rais., some authors have followed 

 Agassiz and others Breynius. At the present time it would be 

 justifiable to reject both of the generic terms, but it is as well to 

 give Breynius credit for recognizing a very interesting form 

 before the days of Agassiz. 



Genus Echinospatagus, Breynius, 1732, Schediasma de Ech. 

 p. 61, pi. V. figs. 3, 4 (pars). Loven, 1874, Etudes., p. 58 

 1883, Pourtalesia, p. 92. 



Syn. Toxaster, Agassiz, 1840 (pars) ; Desor, 1858, Synopsis, 

 p. 350 ; De Loriol, 1888 {Toxaster), Fauae Cret. du Portug., 

 Ech. ii. fasc. 2, p. 92. Miotoxaster, Pomel. 



Test of moderate size, thin, broadly ovoid or subcordate in 

 tumid marginal outline, broadest anteriorly, depressed, swollen 

 dorsally and highest posteriorly, with an anterior shallow, broad 

 groove and a posterior truncation. 



Apical system excentric posteriorly, rarely central, with four 

 perforated basal plates ; the madreporite in the right anterior 

 basal plate, and extending sometimes centrally, but not sepa- 

 rating the posterior radial plates. 



Ambulacra diverse, the anterior in the groove ; the pairs of 

 pores close vertically, and the pores unequal, those of the outer 

 row the longest. Paired ambulacra unequal, subpetaloid, open, 

 flexuous, very slightly sunken or flush, with unequal poriferous 

 zones, and the pores of pairs unequal, the outer elongate 

 and longer than the inner pores ; pairs varying in width, and 

 narrowing towards the end of the petals. Anterior paired 

 ambulacra divergent but directed forwards ; the anterior pori- 

 ferous zones with smaller pairs of pores than the posterior 

 zones. The postero -lateral ambulacra shorter than the others, 



