Ortmann; Families \nd Genera oi Najades. 



319 



discharge of the glochidia. 1 n shell characters Frier son in shows nothing 

 very characteristic, bul it approaches more nearly the Nephronajas- 

 and Eurynia-types than any oilier. 



Friersonia iridella (Pilsbry and Frierson). 



Lampsilis iridella, Pilsbry and Frierson, 1908, p. 81 (figure published in [907, on 

 pi. 12); Pilsbry, 1909, p. 534. 



I have the soft parts of three gravid females, one with eggs, two with 

 glochidia, from Yalles River, Valles, San Luis Potosi, Mexico, and owe 

 them to the courtesy of L. S. Frierson. They were collected by A. A. 

 Ilinkley in December and January, 1906-1907. 42 Cotypes of species. 



mp 



Fig. 19. Friersonia iridella (Pilsbry and Frierson). Gravid female, from Yalles 

 River, Yalles, San Luis Potosi, Mexico. (Cam. Mus., No. 61, 4.495) 



To the characters of the soft parts mentioned in the generic diagnosis 

 the following should be added: Anal and supra-anal separated by a 

 rather short mantle-connection (these parts are greatly injured in all 

 three specimens, but the remnants of the connection may be seen in 

 one specimen). Anal finely crenulated. Branchial with papillae. 

 Palpi rather large, of usual shape, posterior margins connected about 

 one-half of their length. Diaphragm and anterior attachment of gills 

 normal. Gills of gravid female rather long, the outer marsupial 

 gill covering all of the inner gill, except its anterior end. Septa and 

 water-tubes as usual. Marsupium quite long, and formed by a 

 greater part of the outer gill than usual, yet there is a portion at the 

 anterior end and a very small one at the posterior end, which are non- 

 marsupial. Ovisacs over fifty. The sharp edge of the marsupium 



' See Hinkley, 1907, p. 68. 



