EOCENE ECHINODEEMATA. 115 



H. L. Clark, who examined the specimens for Arnold, says that they 



All appear to belong to one species, except possibly one fragment. That piece might possibly have come from quite 

 a different species. I am very glad to see this material of merriami, for it satisfies me that the species must have been 

 allied to, not identical with, Tretoeidaris perplexa Clark (Cidarida;, 1907, p. 205, PL VI, figs. 1-2; PL VII, figs. 1-4) the 

 only other living littoral cidarid known from north of Panama (other, I mean, than thouarsii). So your material 

 shows that the ancestors of both thouarsii and perplexa lived in the Tertiary in California. 



Locality. — Santa Cruz quadrangle, San Mateo County, locality No. 25, ridge between head- 

 waters of San Lorenzo Kiver and Pescadero Creek, Cal. 



Geologic horizon. — Eocene, possible equivalent of Martinez formation. 

 Collection. — U. S. National Museum (165, 438). 



Cidaris mcereus De Gregorio. 



Cidaris mcereus De Gregorio, 1S90, Mon. faune Eocenique Alabama, p. 252, PI. XLIII, figs. 22-23 

 Cidaris rruzreus Stefanini, 1911, Soc. geol. italiana Boll., vol. 30, p. 697. 



Description. — No specimens of this species were available for study. The type form described 

 by de Gregorio evidently came with other materials from the Claiborne in Alabama. The author 

 describes the species as follows: "Aculeus subcylindraceus, oblongus, tuberculis erectis notatis 

 confertis majoribus et minoribus irregulariter dispositis ornatus." 



Locality. — Near Claiborne, Ala. 



Geologic horizon. — Claiborne group, middle Eocene. 



Collection. — De Gregorio. 



Cidaris modestus De Gregorio. 



Cidaris modestus De Gregorio, 1S90, Mon. faune eocenique Alabama, p. 253, PL XLIII, fig. 26. 

 Cidaris modestus Stefanini, 1911, Soc. geol. italiana Boll., vol. 30, p. 697. 



Description. — No specimens of this species were available for study. The type form de- 

 scribed by De Gregorio evidently came with other materials from the Claiborne in Alabama. 

 The author describes the species as follows: "Aculeus augustus, conoideo-cylindraceus, costulis 

 longitudinalibus ornatus; costis crenulatis, granulo-squamosis ; granuhs subimbricatis." 



Locality. — Near Claiborne, Ala. 



Geologic horizon. — Claiborne group, middle Eocene. 



Collection. — De Gregorio. 



Cidaris ordinatus De Gregorio. 



Cidaris ordinatus De Gregorio, 1890, Mon. faune eocenique Alabama, p. 352, PL XLIV, fig. 1. 

 Cidaris ordinatus Stefanini, 1911, Soc. geol. italiana Boll., vol. 30, p. 697. 



Description. — No specimens of the species were available for study. The type form described 

 by De Gregorio evidently came with other materials from the Claiborne group near Claiborne, 

 Ala. The author describes the species as follows : "Aculeus subcylindraceus; tuberculis erectis, 

 raris, subsequalibus, quincuncim atque spirahter regulariter dispositis." 



Locality. — Near Claiborne, Ala. 



Geologic horizon. — Claiborne group, middle Eocene. 



Collection. — De Gregorio. 



