EXPLANATION OF PLATES. 671 
PLATE XXXI. 
Figs. 1, 2. Unio psoricus, Morel. (p. 494) , Rio de Las Salinas: 2a, more elongated form; 1 a, hinge 
Fig. 
Fig. 
Fig. 
Fig. 
of the left valve. 
3. erocodilorum, Morel. (p. 495), a specimen from Paetel’s collection, now in the Berlin 
Museum : 3a and 3 4, hinge of each valve. 
4. corium, Reeve (p. 495), a specimen from Paetel’s collection, now in the Berlin 
Museum: 4.a@ and 4, hinge of each valve. 
PLATE XXXII. 
1. Unio percompressus, v. Mart. (p. 496), Rio de Las Salinas, a somewhat triangular form: 
1a, inside of the right valve. 
a » a younger specimen from the same locality, hinge of the right, 2 a, hinge of 
the left valve. 
3. —— » Rio de Las Salinas, a somewhat quadrangular form: 8a, inside of the right 
valve ; 35, ditto, seen from above. 
4,5. Dreissena sallei, Récl. (p. 477), Honduras, two somewhat different specimens, views 
showing the inside of the right valve, seen from below. 
PLATE XXXIITTI. 
1. Unio tampicoensis, Lea (p. 511), Tampico, from Paetel’s collection: la, right valve, 
inside; 1 0, hinge of left valve. 
discus, var. panucoensis, v. d. Busch (p. 510), Panuco, specimen from Dunker’s 
collection : 2a, right valve, inside; 26, hinge of left valve. 
PLATE XXXIV. 
1. Unio liebmanni, Phil. (p. 500), Mexico, specimen sent by Dr. Moérch of Copenhagen to 
Prof. Dunker: 1 a, right valve, inside; 1 6, ditto, seen from above. 
2. sallei, Cr. & Fisch., var. grossus, n. (p. 517), Rio de Las Salinas: 24a, right valve, 
inside ; 2 4, ditto, seen from above. 
3. rubicundus, u. (p. 514), Coban: 3a, left valve, inside. 
PLATE XXXV. 
1. Unio microdon, v. Mart. (p. 504), Rio de Las Salinas: 1 a, right valve, inside; 1 4, hinge 
of left valve; 1c, ditto, seen from above. 
2. alienigenus, Cr. & Fisch. (p. 513), specimen sent by Dr. Anthony to the Berlin 
Museum: 24, right valve, inside. 
3-5. tampicoensis, Lea, var. umbrosus, Lea (p. 512), Rio Medellin, three different stages 
of growth from the same locality: 5a, right valve, inside ; 5 4, hinge of left valve. 
