EXPLANATION OF THE PLATES. 



NOTE. The figures following the authority for the specific name denote the actual length in milli. 

 meters of the longest diameter of the figure, whether that he the height or the breadth, except where 

 otherwise stated. 



PLATE I. 



FIG. 1. Corbula Krebsiana C. B. Adams; 6.1. 

 1 a. " " 



1 b. " " 



2. Basterotia quadrata Hinds; 10.0; left valve. 



2 a. Same, hinge seen, from above. 

 2b. " " " " below. 



3. Corbula Knoxiana C. B. Adams; 12.7; front. 



3 a. back of left valve. 



3 b. " 



3c. " " 



4. Curbula disparUis D'Orbiguy ; 9.0. 



4 a. " " 



4 b. " " 



5. Corbula Dietziana C. B. Adams; 10.7. 



5 a. " " 

 5b. " '" 



6. Corbula KjoerianaC. B. Adams; 12.0 



6 a. " " 

 <5b. " " 



7. Corbula cymella Dall ; 13.5. 



All the above, except figures 2 a, 2 b, and 4 a, 4 b, are drawn by W. H. Dall with 

 the camera lucida from typical specimens of the describer in the museum at Am- 

 hersr. 



The following plates (I-XL) arc from the Report on the Mollusca of the Blake Expedition, parts I 

 and II, drawn by J. C. McUonnell (except where otherwise stated) from the specimens. For the use 

 of these plates we are indebted to Prof. Alex. Agassiz. 



PLATE II. 



FIG. 1 a, 1 b. Ferticordia (Euciroa) eleyantissima Dall ; 13.25. 



2, 2 a. Halonympha claviculata Dall ; 12.0. 



3 a, 3 b. Cardiomya perrostrata Dall ; 8.0. 



4 a, 4 b. Verticordia (Haliris) Fischeriana Dall ; 10.0. 



5 a-5 c. Corlula Swiftiana C. B. Adams, from type ; 10.4. 



6 a-6 d. Corbula Chittyana C. P-. Adams, from type; 8.5. 



7, 7 a-c. Corbula Barrattiana C. B. Adams, from types; 8.9. 



177 

 24731 Bull. 37 12 



