516 MOLLUSCA. 
Var. carbonarius. 
Unio carbonarius, Lea, Trans. Am. Phil. Soc. vi. p. 37, t. 11. fig. 382 (1836) *; Obs. Gent Uniosa ii. 
p. 87, t. 11. fig. 32"; Synopsis of Unionide, ed. 4, p. 31 (1870) “; Hanley, Cat. Rec. 
Bivalv. p. 184, t. 22. fig. 10, and t. 23. fig. 12”. 
Ventral margin sinuated. 
Hab. E. Mexico: Rio Medellin (Dr. Burrough '? }*). 
Lea 12 13 mentions no plaits in the description, but as his type was much worn over a 
great part of the surface, they may have been present in a younger state and disappeared 
afterwards by external injury: he says that his specimen is probably very old. 
45. Unio ravistellus. (Tab. XX XVIII. figg. 2-6 a.) 
Unio ravistellus, Morelet, Test. Noviss. i. p. 29 (1849)*; Kiister, in Martini & Chemnitz, 
Syst. Conch.-Cab. ed. 2, Unio, p. 145, t. 42. fig. 6°; Sowerby, in Reeve’s Conch. Icon. 
vi., Unio, t. 72. fig. 366°; Fisch. & Crosse, Miss. Scient. Mex., Moll. 1. p. 609, t. 61. 
figg. 4,5, 5a’. 
Of small size, rather thin, kidney-shaped, dorsal margin in the hinder part arcuated, ventral margin more or 
less sinuated ; usually much eroded, chiefly behind the summits in larger patches. Cardinal teeth small, 
triangular, furrowed. Inside of the shell lead- coloured. 
a. Long. 38; alt. vert. 22, ale ?, diam. 12 millim. Vertices in 3 long. 
b. ” 39 3 ” 21, 9 194, ” 134 ” ” 3 ” 
C. ” 40; ” 17, ,, 19, ” ? ” ” 3 ” 
d. ” 35 ; ” 183, » 18, ” ? ” ” 4 
a. Measurements given by Morelet'; 6, d. Figures given by Fischer ‘and Crosse *; c, by Kiister *. 
Hab. EB. Guatemata: Lake of Yzabal (Morelet1+); Guatemala, without nearer 
indication of locality (Charpentier). 
The specific name ravistellus is derived from the Latin ravus, grey: this term was 
probably used to describe the colour of the inside of the shell, the outside being dark 
brown, as in most other species of the genus. 
Var. majusculus. 
Of larger size; the summits somewhat more advanced. 
a. Long. 59; alt. vert. 27, alee 28, diam. 173 millim. Vertices in 2 long. 
b. 99 58 5 29 26, 99 27, 29 117i 99 99 
«. » «995 ” 26, ,, 27, » «20 ” 
Hab. EK. Guatemata: Lake of Yzabal (Séol/). 
99 
sao “aldo 
99 29 
The dimensions given show that this form varies considerably in the general outlines. 
Var. verepacis. (Tab. XX XVIII. figg. 1, 1 a.) 
Unio verepacis, Tristram, P. Z. 8. 1863, p. 414’. 
Unio vellicatus, Sowerby, in Reeve’s Conch. Icon. xvi., Unio, t. 22. fig. 103 (1865) °. 
Of smaller size, the summits more advanced, the hinder part bent downward ; inside purplish-brown. 
a. Long. 43; alt. vert. 19, ale 20, diam. 15 millim. Vertices in 4 + long. 
bu 6, «645; » 22, 28, 2s, i 
99 bh) 
a. Tristram’s type ; 6. Sowerby’s figure. 
Hab. E. Guaremata: Vera Paz (Salvin ®); Panzos (Conradt, in Mus. Berol.). 
” q 9» 
