512 MOLLUSCA. 
Var. tecomatensis. 
Unio tecomatensis, Lea, Proc. Am. Phil. Soe. ii. p. 80 (1841) °; Trans. Am. Phil. Soc. (2) viii. 
p. 234, t. 21. fig. 48°; Obs. Gen. Unio, iii. p. 72, t. 17. fig. 48°; Chenu, Illustr. Conch., 
Unio, t. 30. fig. 6"; Fisch. & Crosse, Miss. Scient. Mex., Moll. ii. p. 589, t. 65. fig. 6, and 
t. 66. fige. 4, 4a”. 
Unio tampicoensis (Lea), Kiister, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Unio, p. 275, 
t. 93. fig. 1”. 
More convex, anterior tooth somewhat stronger ; inside purple-violet. 
a. Long. 89; alt. vert. 55, ale 58, diam. 1 millim. Vertices in 3 long. 
& 64, 98 ” 64, ,, 61, ,, 40 ,, 9 3 9 
Hab. E. Mexico: Rio Tecomate, near Tlacotalpam, State of Vera Cruz (Dr. 
Burrough®—"2);| Rio Cosamaloapam, an affluent of Rio Alvarado, near Cha- 
coltianguis (Sadlé 1°). 
Var. umbrosus. (Tab. XXXYV. figg. 3-5 6.) 
Unio tampicoensis (younger specimens), Lea, Obs. Gen. Unio, ii. p. 24". 
Unio umbrosus, Lea, Proc. Acad. Phil. viii. p. 95 (1857); Journ. Acad. Phil. (2) ii. p. 318, 
t. 30. fig. 26°°; Obs. Gen. Unio, vi. p. 31, t. 30. fig. 26°"; Sowerby, in Reeve’s Conch. 
Icon. xvi., Unio, t. 28. fig. 170; Stearns, Proc. U.S. Nat. Mus. xiv. p. 103 (1891); 
Fisch. & Crosse, Miss. Scient. Mex., Moll. ii. p. 587, t. 67. figg. 1, 1 a, 6”. 
Somewhat more oblong, with straighter ventral margin; outside rather blackish, inside pale purple, in some 
specimens with an orange band along the pallial line. In full-grown specimens (the young one, h, 
excepted) the middle of the inside is beset with a number of granules, probably of extraneous origin, but 
fixed to the shell by the last layer of calcareous matter. 
a. Long. 89; alt. vert. 48, ale 414, diam. 35 millim. Vertices in ? long. 
b. » 97; ” 50, ,, 54, » 37 ” ” % 9 
c. ” 84 ; » 47, ” 52, ” 32 ” ” + ” 
d. 4, T7;3 - 45, ,, 454, ,, 29 ~~ ,, * 3 9 
é. » 105 rT) 42, ,, 50, » 3h ” 2 2 ” 
f. », 89; ” 39, 4, 44, » 29 ” ” 3 ” 
Je 60 ; ” 33, 4, 39, » «=o ” ” 4 ” 
h 4, 573 ” 30, , 338, 4 19 2 
” 9 7 99 
a. From Lea’s figure; d. A specimen collected by Strebel in the Medellin river, unusually inflated behind, 
probably a female; 6, c, e-g. Specimens collected by H. H. Smith; hk. The youngest of Strebel’s examples. 
Hab. N.E. Mexico: Rio Salado, State of Nuevo Leon (Lloyd }9). 
E. Mexico: Rio Medellin (Dr. Burrough %—1", Sallé*°, Strebel, H. H. Smith). 
The above-mentioned granules are probably grains of sand introduced into the 
interior of the shell, and therefore not of specific value, but it must be noted that they 
are found in all known full-grown specimens: Lea does not mention them in the 
description, though they are visible in his figure. They may be due to a peculiarity 
of the locality. 
The specimen ¢ somewhat approaches U. alienigenus, the hinder part being more 
inflated than usual. 
