MOLLUSCA OF PORTO RICO. 
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there are delicately crimped longitudinal frills. Sometimes the revolving ridges between the larger 
ones are flattened as though they had been pressed when in a soft state; canal rather short, nearly 
closed when the shell is fully adult. Color ashy white, often faintly banded with brownish. 
Length, 20; diameter, 10 mm. 
Mayaguez, Porto Rico; Vieques. One young shell from each, that from the former havingthe ribs 
compressed. 
This species is distinguished from Kiener’s figure of alveolus by its more acute apex and its more 
dense and frothy sculpture of the revolving ridges; but we do not feel assured of their specific 
distinctness in the absence of specimens of M. alveolus. 
Genus MURICIDEA (Swainson) Morch, 1840. 
Shell with elevated spire and a canal of moderate length, longitudinally ribbed, but lacking the 
primary varices of Murex; ojrerculum fusoid, with an apical or almost apical nucleus. 
A genus of doubtful homogeneity. In such species as M. floridana and M. multangula there are 
only longitudinal ribs, which are not at all varix-like. In others the ribs take on the nature of varices 
to some extent, and are sometimes as well developed as in the typical Murices. 
Subgenus Muricidea s. s. 
Muricidea hexag-ona Lamarck. 
Murex hexagonus Lamarck, An. sans Vert., vii, p. 169, 1822. 
Murex hexagomis Reeve, Conch. Icon., in, pi. xxvit, fig. 120, 1845. 
Shell rather elongated, with eight or nine whorls, and six spiny rib-like varices; spines short, 
slightly upcurved, only a single one to each varix on the upper whorls, about six on each varix of 
the body whorl and the canal; these are open in front; sculpture consisting of low, rather sharp, 
revolving ribs, which on the varices develop into the spines; the spaces between these ribs is concave. 
Outer lip toothed within; inner lip generally somewhat raised at its edge. Color whitish; the spines 
often purple, and sometimes the shell has purplish tints. 
Length, 35; diameter, across the spines 23, across the body whorl 15 mm. 
Ponce Reefs, Gallardo Bank, Porto Rico. 
Subgenus Pseudoneptunea Kobelt, 1882. 
Muricidea multangula Philippi. 
Fusus multangulus Philippi, Zeits. fur Mai., v, 1849, p. 25; Abbild. und Beschr., m, p. 117, pi. xxiv, fig. 6,1850. 
Shell with eight somewhat shouldered whorls, which are crossed by about seven strong, rounded, 
longitudinal ribs; the surface is covered with revolving sculpture consisting of rather strong threads, 
of which about every fourth one is larger; aperture ovate-elongate; outer lip hardly thickened, feebly 
lirate within; canal short, open; columella curved, with a single ridge below; behind it there is a false 
umbilicus. Color yellowish or whitish, with small brown spots or blotchings, which are sometimes 
imperfectly arranged in longitudinal and revolving series. Sometimes there are faint longitudinal 
streaks, and occasionally the shell is feebly banded. 
Length, 30; diameter, 17 mm. 
One very young shell was obtained at Mayaguez. 
Genus ASPELLA Morch, 1877. 
Shell elongated, with elevated spire and a short, recurved, nearly closed canal; surface of a peculiar 
spongy or chalky white character, which when worn away reveals a shell of solid texture, white 
or brownish; there is a set of two or three principal varices and often a smaller secondary set, and 
besides these there are sometimes irregular longitudinal ribs; surface covered with revolving strife, 
often somewhat pitted; aperture small, elliptical; outer lip usually feebly toothed; there is a false 
umbilicus at the base of the columella. 
Type, Ranella anceps Lamarck. 
There is a general agreement of the important characters of the species forming this group, the 
peculiar texture, form of canal and aperture, revolving sculpture, and varices being found in all of 
