Clark: The San Lorenzo Series of Middle California 143 



DOSINIA (DOSINIDIA) WHITNEYII (Gabb) 

 Plate 7, figures 3 and 4 



Chionc whitneyii Gabb, Geol. Surv. Calif., Palaeontology, vol. 2, p. 23, pi. 5, 

 fig. 40, 1866. 



This species, which was originally described by Gabb as a Chione 

 from a rather fragmentary specimen, appears to be distinct from 

 D. mathewsonii Gabb ; it is higher in proportion to the length, the 

 beaks are more prominent, it is not so strongly produced anteriorly 

 and the lunule is larger. The concentric sculpturing of the two forms 

 is the same. 



Genus ANTIGONA Shumaeher 

 ANTIGONA (ARTENA) MATHEWSONII (Gabb) 

 Plate 15, figures 5, 6 and 7 



Chione mathewsonii Gabb, Geol. Surv. Calif., Palaeontology, vol. 2, see. 1, 



p. 23, pi. 5, fig. 39, 1866. 

 Chione mathewsonii Gabb, Merriam, Univ. Calif. Publ., Bull. Dept. Geol., 



vol. 3, no. 16, p. 378, 1904. 

 Chione mathewsonii Gabb, Smith, Proe. Calif. Aead. Sci., ser. 4, vol. 3, 



p. 171, 1912. 



Chione mathewsonii Gabb, San Francisco Folio 193, U. S. Geol. Surv., p. 11, 

 1914. 



MacrocaUista? mathexvsonii Gabb, Clark, Univ. Calif. Publ., Bull. Dept. 

 Geol., vol. 9, no. 2, p. 14, 1915. 



Gabb 's description of the type is as follows : 



Shell very thick, obliquely cordate, very inequilateral ; beaks anterior ; anterior 

 end sinuous ; base broadly rounded ; posterior end prominent, narrow. Lunule 

 lanceolate, impressed. Surface marked by numerous irregular, concentric ribs ; 

 adjoining the cardinal edge and posterior to the beaks is a narrow space running 

 almost to the posterior end of the shell ; inner margin entire, not crenulated. 

 Pallia! sinus deep ; lower side curved, upper side straight. 



The hinge plate and the escutcheon of this species show that it 

 belongs to the genus Antigona; Antigona equals the old genus 

 Cytheria Bolton. Dr. W. H. Dall informs me that the name Cytheria 

 "is preoccupied in insects by Fabricius; the next oldest name, Anti- 

 gona Schumacher, 1817, not Roemer, will have to be adopted for the 

 genus." On the left valve the middle cardinal is heavy and bifid; 

 the posterior cardinal is long and narrow and is situated on top of 

 the nymph plate ; the anterior lateral is long, pointed and rather 

 low. The posterior cardinal of the right valve is bifid, as is probably 



