Belomitra pourtalesii is a species of sea snail, a marine gastropod mollusc in the family Belomitridae.

(Original description) The slender, dull, light brown shell is eight-whorled.

The posterior terminations of these riblets are waved, forming an obscure notch-band, each being slightly enlarged close by the suture and also on the anterior side of the band, thus forming two rows of indistinct nodulations, of which the sutural row is more clearly defined than the other.

Here eight or ten rather indistinct revolving threads exist, becoming more distinct toward the end of the siphonal canal, separated from each other by shallow grooves.

[2] This species occurs in the Caribbean Sea and the Gulf of Mexico; off the Lesser Antilles; in the Atlantic Ocean off Georgia.