360 Annals of the Carnegie Museum. 



than in T. florentina. The inner edge scarcely shows papilla?, 

 but this may be due to lack of development or to the state of preser- 

 vation of the specimens. The outer edge is slightly wavy, but has 

 no teeth. 



Charged marsupium not observed, but the marsupium is indicated 

 in the sterile female by a series of white beads along the posterior half 

 of the edge of the outer gill. 



In the male the two edges of the mantle are subparallel and only 

 slightly distant from each other, and posteriorly the color of the 

 margin of the mantle consists of black spots, which are hardly notice- 

 able in the female. 



There remains the Family Mittelidce, with its two subfamilies (see 

 above, p. 225) to be treated. My studies on these have been previously 

 published (Ortmann, 1911c), and are yet rather incomplete. Since 

 I have not investigated additional material, I cannot add anything 

 to these preliminary results, and do not need to repeat them here. 

 But my next undertaking will be to study the South American material 

 of this family belonging to the Carnegie Museum, and these investi- 

 gations will be published in due time. 



Bibliography. 



1898. Baker, F. C. The Mollusca of the Chicago Area (Bull. Chicago Acad. Sci., 

 3, part 1, pp. 47-110). 



1880. Bourguignat, J. R. Materiaux pour servir a 1'Histoire des Mollusques 

 Acephales du System Europeen. 



1895. Call, R. E. A study of the Unionidse of Arkansas, with incidental refer- 

 ence to their distribution in the Mississippi Valley (Tr. Acad. Sci. 

 St. Louis, 7, pp. 1-64). 



1910. Carl, S. Die Flussperlmuschel und ihre Perlen. Karlruhe, 100 pp. 

 1876. Clessin, S. Deutsche Excursions-Mollusken-Fauna. 



191 1. Coker, R. E. and Surber, T. A note on the Metamorphosis of the mussel 



Lampsilis laevissimus (Biol. Bull., 20, pp. 179-182). 

 1907. Conner, C. H. The gravid periods of Unios (Nautilus, 21, pp. 87-88). 

 1909. Conner, C. H. .Supplementary notes on the Breeding Seasons of the 



Unionidae (Nautilus, 22, pp. 111-112). 

 1853. Conrad, T. A. A Synopsis of the Family of Najades of North America, 



etc. (Pr. Acad. Sci. Philadelphia, 6, pp. 243-269). 

 1909. Dall, W. H. Descriptions and Figures of some Land and Freshwater Shells 



from Mexico, believed to be new (Pr. U. S. Mus., 35, pp. 177-182). 

 1875. Flemming, W. Studien in der Entwicklungsgeschichte der Najaden (S. B. 



math.-naturw. CI. Akad. Wiss. Wien, 71, Heft 3, pp. 81 ff.). 

 1901. Frierson, L. S. A new Cnio from Texas (Nautilus, 15, pp. 75-76). 



