102 MONOGRAPH OF THE GENUS GNATHODON—DALL. vol. xvii. 



GNATHODON (RANGIANELLA) MENDICIJS, Gould. 

 Plate VII, fig. 2. 



Macira mendica, Gould., Proc. Bost. Soc. Nat. Hist., iv, p. 88, Nov., IS.'')! ; Journ. B. 



S. N. II., VI, p. 393, PI. XV, fig. 4, Oct., 1853. 

 Gnathodon mendicus, Caupenteu, P. Z. S. 1856, p. 200; Mazatlau 81i., p. 549, 1857; 



Eep. Br. Assoc. 1863, pp. 535, 543, 592. 

 Gnathodon irUjonuyn, Petit, Journ. do Couchyl. iv, pp. 84, 166, PI. vi, figs. 13-15, 



18r)3.— Carpknteu, p. Z. S. 1856, p. 200; Rep. Br. Assoc. 1857, p. 227 ; Rej). Br. 



Assoc. 1863, pp. 535, 543, 576, 592, 633. 

 Gnathodon trUjona, Cahpknter, Mazatlau Sh., p. 52, 1857. 

 Gnathodon inmcatum, Petit, Journ. de Conchyl. iv, p. li, of expl. pi., 1853. 

 Gnathodon Lccontei, Coxkad. Proc. Acad. Nat. Sci., vii, p. 31, 1854; not of 



Conrad, Journ. Acad. 1853. 

 Bangia trigona, Adams, Gen. Rec. Moll, ii, p. 380, 1858. 

 Rangia mendica. Prime, Proc. B. S. N. H. vii, p. 347, 1861. 

 liangianella irigona, Conrad. Am. Jour. Conch., iii, suppl., p. 30, 1868. 



Mazatlau, Mexico, Lieut. Green, Rollaiul de Eoqnan, Eeigen, etc.; 

 living in brackish water. 



I have examined authentic specimens of both G. mendicus and G. trigonus 

 and there seems to be no doubt of their identity. 



The ei)idermis of this species is of a straw color, varying to greenish 

 yellow, darker on the posterior slope, where it often becomes fibrous, 

 and having a paler lozenge shaped area over the hinge, which, however, 

 is not circumscribed by any groove. Internally the shell is i)olished 

 outside of the area inclosed by the pallial line. The latter is feebly 

 waved, but hardly indented. The lateral teeth are nearly equal, feebly 

 gran ulose, the anterior with the " hook " almost obsolete. Although 

 the shell usually has a smooth internal margin it is sometimes radiately 

 striated, especially above the hinge, and the lines of growth are often 

 beaded here and there with short radiating threads much more regular 

 and distinct than those sometimes notable on G. cuneatns. A faint 

 wrinkled sculpture is constantly present on the posterior slope and 

 seems characteristic of the species. The umbones are quite smooth. 

 The specimens I have seen average about 25 mm. (1 inch) in length, 

 18 mm. in height, and 12.") mm. in diameter. 



GNATHODON (RANGIANELLA) FLEXIIOSUS, C on r ad . 

 Plate VII, figs. 3,6. 



Gnathodon flexuosns, Conrad, Am. Journ. Sci., 1st ser., xxxviii, p. 92, fig. 1839; 



Proc. Acad. Nat. Sci. Phila., vii, p. 31, 1855. 

 Gnathodon rostratum. Petit, Journ. de Conchyl. iv, pp. 84, 164, PI. v., figs. 



1-3, 1853. 

 liangia fiexuosa, Conrad, Proc. Acad. Nat. Sci. Phila. for I860, p. 232; Am. 



Journ. Conch., iii, supplem., p. 30, 1868. 

 Bangia rostrata, Prime, Proc. Bo,st. Soc. N. Hist., vii, p 348, 1861. — Adam.s, 

 Gen. Rec. Moll., ii, -p. 380, 18.58. — Conrad, Am. Journ. Conch., iii, suppl., 

 p. 30, 1868. 

 Living on the coast of the Gulf of Mexico from northern Florida to 

 Vera Cruz, Mexico, in suitable places. Apparently a denizen of pure 

 salt water. 



