2 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.71 



The history of the species is shown below: 



MYCETOPODELLA FALCATA (Higgins) Marshall 



Plate 1, fig8. 1-3 



1868. Mycetopus falcatus Higgins, Proc. Zool. Soc, London, p. 179, pi. 14, fig. 6. 

 1868. Mycetopus falcatus Higgins, Sowerby, Conch. Icon., vol. 16, pi. 4, fig. 9. 

 1870. Platiris (Mycetopus) falcatus (Higgins) Lea, Synopsis, p. 90, 

 1875. Mycetopus falcatus Higgins, Clessin, Conch. Cab., p. 204, pi. 67, fig. 12. 

 1875. Mycetopus falcatus Higgins, Fischer, Journ. de Conch., vol. 38, p. 8. 

 1900. Solenaia falcata (Higgins) Simpson, Synopsis Naiades, Proc. U. S. Nat. Miis., 



vol. 22, p. 656. 

 1914. Solenaia falcata (Higgins) Simpson, Descr. Cat. Naiades, vol. 1, p. 458. 

 1916. Mycetopoda bolivari Haas, Trabajos Mus. Nacional de Ciencias Naturales, 



Madrid, Zool. Ser., No. 25, p. 57, fig. 2. 



1925. (Genus?) falcata (Higgins) Marshall, Microscopic sculpture of pearly, 



fresh-water mussel shells, Proc. U. S. Nat. Mus., vol. 67, pp. 10-12, pi. 

 4, fig. 1. 



1926. Mycetopoda falcata (Higgins) Ihering, Nautilus, vol. 39, p. 116. 



This is one of the most interesting shells in the whole group of 

 pearly fresh-water mussels. It resembles Mycetopoda but lacks the 

 smooth, shining periostracum and differs in microscopic sculpture, 

 in the falcate form and in the peculiar downward bending anterior 

 end. It resembles also Solenaia, especially the species emarginata 

 Lea of Siam, of which it is almost an exact miniature. The resem- 

 blance is remarkable in that the anterior end of the shell curves 

 abruptly downward in both genera and gives a falcate form to the 

 shells. They also resemble each other in color and in dullness and 

 general appearance of periostracum. They differ in habitat — Solenaia 

 living in Southeastern Asia Mycetopodella in South America, so far 

 as known at present in the upper Amazon. They differ also in the 

 structure of the periostracum. At present this is the most important 

 difference known. The microscopic sculpture of Mycetopodella is com- 

 posed of numerous radiating striae which prove the shell to belong 

 in the family Mutelidae. Solenaia does not have this style of sculp- 

 ture and this is an indication that it is not a Mutelid. This belief is 

 further strengthened by the anatomy of Solenaia which shows it to 

 belong to the Tetragenae in the family Unionidae. 



Marshall ^ discusses the microscopic sculpture on the periostracum 

 of Mycetopodella falcata and the absence of close relationship between 

 this shell and the genus Solenaia. The superficial resemblance 

 between the two genera is remarkable. It is paralleled in other cases 

 in which there is a superficial appearance of relationship or perhaps a 

 real affinity between South American and southeastern Asiatic shells. 

 The genus Acostaea (Mulleria) ,ior instance, is supposed to include two 

 species, A. lohata Ferrussac (the type of the genus), which occurs in 



> Proc. U. S. Nat. Mus., vol. 67, 192.'i, pp. 10-12. 



