264 AXEL A. OLSSON 



This species has generally been considered a synonym of the more 

 southerly C. subqiiadrata Hanley to which it is obviously related, but it 

 differs by its more circular form (see figures), the posterior-dorsal margin 

 is shorter, less sharply descending at the end, and the anterior side is 

 longer; internally, the posterior adductor scar is placed much lower, and 

 the pallial sinus is directed upwards towards the hinge and not towards 

 the anterior adductor scar. 



Range — Gulf of California to Panama. Panama: Gulf of Panama 

 (shrimpers); Biicaro. Mexico: Mazatlan. 



Cyclinella ulloana Hertlein and Strong Plate 43, figure 3 



Cyclinella kroyeri ulloana Hertlein and Strong, 1948, Zoologica, vol. 33, pt. 4, pp. 179, 

 180, pi. 2, figs. 5, 6, 7. 



Shell orbicular, dosinoid, white, moderately inflated, moderately thick; 

 sculptured by fine but well developed concentric lines of growth; pallial 

 sinus fairly broad, short, rounded at the end, projecting about 33 mm. from 

 the posterior margin toward the anterior muscle impression; margin smooth. 

 Dimensions: length 75.5 mm., height 76.5 mm., convexity (one valve), 

 19 mm.— (Hertlein and Strong, 1948.) 



Holotype, Santa Inez Bay, Gulf of California. 



This species is similar to C. galera Pilsbry and Olsson (Proc. Acad. 

 Nat. Sci. Philadelphia, vol. 93, p. 66, pi. 12, fig. 1; pi. 19, fig. 4), but an 

 actual comparison of specimens have not been made. Both C. galera and 

 C. ulloana differ from other Panamic species in that the height of the shell 

 is a little greater than their length and also in having the posterior side 

 narrower and somewhat contracted. 



Range — Gulf of California. 



Cyclinella jadisl, new species Plate 43. figures 2. 2a 



Shell of medium size, subcircular, slightly convex, the zone of greatest 

 inflation lying along the posterior-umbonal slope. External surface of valves 

 covered with minute, concentric growth lines, and because of their fine, 

 close spacing, often produce a sheen or luster like that of silk. Pallial sinus 

 large and narrow, extending to about the middle of the shell cavity. Color 

 white, often with the umbones stained red or amber-brown. The lunula is 

 small, subelliptical, flat and not sharply outlined. 



Length 61.5 mm., height 60.3 mm., diameter 26.4 mm. Holotype, ANSP 

 218900. 



Length 67.7 mm., height 65.2 mm., diameter 27.8 mm. 



I take much pleasure in dedicating this species to Mr. Stewart H. Jadis, 

 a well-known collector of Panama shells for many years, and for his com- 

 panionship on many a field trip in the Canal Zone as well as in Panama 

 itself. 



Range — Panama southward to Ecuador. Panama: Panama City; Pearl 

 Islands. Panama Canal Zone: Palo Seco. Ecuador: Manglaralto; Santa 

 Elena. 



