ARNOLD — THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 91 



Pleistocene (lower San Pedro series) deposits at the bath-house, Santa Barbara. 

 A nearly perfect test was also found in the upper horizon of the San Diego 

 formation (Pleistocene(?) at Pacific Beach, near San Diego. 



Living. — San Francisco; Puget Sound (II. L. Clark) : San Pedro (Arnold). 



Pleiatocene. — San Pedro; Santa Barbara; San Diego (Arnold). 



Order CLYPEASTROIDA. 



Family III. SCUTELLID^. 



Genus Scutella Lamdrck. 



Test circular or subcircular in outline, sometimes undulating or notched, broadest behind ; 

 petaloid parts of the anib unequal, well developed, nearly closed. Peristome small, central, subcir- 

 cular. Periproct very small, inframarginal. Apical system central, more or less pentagonal. 



Subgenus Echinarachnius Leske. 

 Apical system eccentric in front or behind. Periproct actinal, marginal or supramarginal. 



7. Scutella (Echinarachnius) excentricus Esehscholtz. 



Scutella excentrica EscH., Zool. Atlas, PI. XX, fig. 2, 1826. 



Echbiarachnius excentricus EscH., Valenciennes, Voyage Venus, PI. X, \'i,\i>\^=Scutella striatula 



Con. {Jide Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 271). Merriam, Bull. Dept. 



Geol., Univ. of Cal., Vol. II, 1898, p. no; Proc. Cal. Acad. Sci., 3rd Ser., Geol., Vol. I_ 



1899, p. 170, PI. XXII, fig. 8. 



Test quadrate-oval in outline ; upper surface arched, summit behind the middle of the long 

 diameter, but in front of the e.vcentric apical system ; petals broad, open at ends ; posterior laterals 

 wide apart, ovate in outline, one-half the length of the anterior pair ; anterior petal longer than the 

 anterior laterals, scattered pores continue some distance beyond the end ; apical shield excentric, its 

 distance from the posterior margin being to its distance from the anterior margin as I to 1.8+ : the 

 ambuiacral furrows are split up into a great number of small branches, of which the strongest pass 

 over the margins and extend over the upper surface ; four of the strongest furrows run to the lateral 

 petals and stretch through their median areas almost to the apical system ; those furrows not passing 

 to the petals sometimes reach half way to the apical system. 



Dimensions. — Long. 63 mm.; lat. 68 mm.; alt. 8 mm. 



Specimens from the lower San Pedro series of Deadman Island, and upper 

 San Pedro series of San Pedro and Los Cerritos were submitted to Dr. Merriam, who 

 pronounced them typical E. excentricus. This is the common "Sand Dollar" of the 

 Pacific Coast. 



• Living. — Alaska to San Pedro (Cooper). 



Pleistocene. — San Pedro (Cooper; Arnold) : San Diego; Santa Barbara (Arnold) 



f?J Pliocene. — Seven I\Iile Beach, San Mateo County; San Fernando; (?) San 

 Diego (Cooper): (?)San Gregorio Creek, San Mateo County (Barber). 



