ORTMANN: FAMILIES AND GENERA OF NAJADES. 319 
discharge of the glochidia. In shell characters Friersonia shows nothing 
very characteristic, but it approaches more nearly the Nephronajas- 
and Eurynia-types than any other. 
Friersonia iridella (Pilsbry and Frierson). 
Lampsilis iridella, Pilsbry and Frierson, 1908, p. 81 (figure published in 1907, on 
pl..12); Pilsbry, 1909, p. 534. 
I have the soft parts of three gravid females, one with eggs, two with 
glochidia, from Valles River, Valles, San Luis Potosi, Mexico, and owe 
them to the courtesy of L. S. Frierson. They were collected by A. A. 
Hinkley in December and January, 1906-1907.%  Cotypes of species. 
Fic. 19. Friersonia iridella (Pilsbry and Frierson). Gravid female, from Valles 
River, Valles, San Luis Potosi, Mexico. (Carn. 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 papille. 
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 
42 See Hinkley, 1907, p. 68. 
