NAIADES OF MISSOURI 103 
Genus Fusconaia Simpson. 
1900b— Fusconata Simpson, Pr. U. S. Nat. Mus. XXII, p. 784 (as sect.) 
1912b—Fusconaia (Simpson) Ortmann, An. Car., Mus., VIII, pp. 
240-241. 
(Tpye Unio undatus Barnes). 
ANIMAL CHARACTERS:—Branchial opening with dense yellow- 
ish tentacles; anal smooth; supra-anal separated from anal by 
very short connection, laminae of inner gills free from visceral 
mass; palpi rather large; all four gills marsupial, ovisacs when 
gravid subcylindrical; conglutinates same shape, usually reddish, 
subsolid and discharged whole; glochidium subovate, somewhat 
small, spineless; colors of soft parts usually brilliant, such as 
orange or red. 
SHELL CHARACTERS:—Shell roundly quadrate or triangular; 
disk smooth; beaks elevated, sculptured with concentric ridges 
angled at base of prominent post-umbonal ridge; epidermis 
reddish to brown with fine, rather interrupted, rays when young; 
hinge teeth well developed; beak .cavities deep; nacre white. 
MISCELLANEOUS RFMARKS:—Dr. Ortmann considers this 
genus the most primitive of the Uxzonidae and limits it to those 
species of Simpson’s trigona group that possess subcylindrical 
conglutinates and ovisacs, concentric beak sculpture and smooth 
disk as the diagnostic features. While the conglutinates of the 
Fusconata species may be reddish, yet they may vary from pale 
pink to white due to their development usually. It is to be noted, 
however, that when the conglutinates are white all of the anatomy 
is also white; when the conglutinates are reddish the soft parts 
will be more yellowish. In this state the following groups. may 
differ morphologically and ecologically as follows: 
1. F. undata: swollen, high beaks, mostly greenish—black 
CIMA Past eter: Toe erty oot AS 2 Big Rivers 
2. F. trigona: swollen, lower beaks, mostly reddish epider- 
SAAR Met RAP Me see eM MN OPAL Medium Rivers 
3. F. flava: flat, low beaks, always reddish epidermis 
Small Rivers 
The second group is not found in very typical form in this 
State, but is represented by intergrading forms. In fact none of 
these Species, representing the above names, are very often found 
typical in Missouri, since this State seems to be the home mostly 
