178 MAZATLAN UNIVALVES 
Tablet 811 contains a sketch of a solitary specimen which 
was found by Mr. Archer among the small shells. It was 
referred by Mr. Cuming to Bulinus Broderipii, Sow. in Proc. 
Zool. Soc. 1832 :—Conch. Ill. f. 1. (=Plectostylus Broderipu, 
HI. & A. Ad. Gen. 11. 155:) but as it doe’ not accord with the 
figures of that Chilian species, it was perhaps an oversight. 
Lamarck’s description might also serve for B. Ziegleri, which 
this shell very greatly resembles. It is however more inflated 
and thinner. Long. '65, long. spir. °35, lat. °4. 
Hab.—Mexico, Humboldt &§& Bonpland.—? Mazatlan; 1 sp. 
with B. Ziegleri; Z’pool Col. 
Orprr LIMNOPHILA. 
Famity AURICULID &. 
Genus MELAMPUS, Mont. 
Melampus, Montf. Conch. Syst. 1810. 
Conovulus, Zam. 1812. This genus was afterwards suppressed 
by its author, and united to Auricula. 
235. MELAMPUS OLIVACEUS, 7”. Ss. 
M. t. parva, sublevi, conoided, spird depressa, intra suturam 
indistinctam obscure angulatdé ; albida fusco-purpureo wrregu- 
lariter tessellatd, epidermide adherente olivaced induta ; anfr. 
vil. vie monstrantibus, planatis ; apertura longa, angusta, ad 
marginem fusco-purpured, intus albé ; labro ad marginem acuto, 
intus dentato, dentibus in liras acutas, in adulté sepe obsoletas, 
decurrentibus ; labio tenut, plict und parietali transversa, inter 
denticulas duas sitd, in guniore denticulis numerosis intus 
conditis ; columella plicd und obliqua, ad basin excurrente ;— 
parietibus interns in adulté absorptis. 
Melampus bidentatus, Moerch in Mus. Cum.: non Say. 
Moerch must surely have been in error in regarding this 
species as a variety of M. bidentatus. It is much more nearly 
allied to the Voluta coffea of Linn. The specimens, of which 
many hundreds were sent, are very constant in the characters 
above given; of which the most distinguishing are the olive 
green epidermis, with the irregular purplish brown tessellated 
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