Characters of the genus Pedipes. 297 
Testa solida, ovalis, striis spiralibus sculpta, unicolor. Spira brevis. 
Apertura ringens, superne integra. Epidermis nulla. 
Animal littorale, revera marinum, et branchiis spirans. 
The remarkable shape of the foot, inducing a corresponding pecu- 
liarity in the mode of crawling, (well described by Adanson), is the sole 
external character by which the animal of the present genus is distinguish- 
able from Melampus. Yet this character, combined with those of the 
shell, is surely enough to warrant their separation. Iam indeed inclined 
to believe, that the different modificaticns in shape of the foot, will, in 
many cases, be found to afford valuable aid, to a more natural and 
scientific arrangement of the marine Gasteropoda into genera, than the 
present state of our knowledge permits. 
The genus Pedipes was founded long ago by Adanson; and both its 
animal and shell are admirably and correctly described by him. Yet 
Bruguiére united it with his Bulimi; and Lamarck has confounded it 
with Tornatella. 
The species from which the above description and accompanying draw- 
ings were made, I once considered distinct from Adanson’s species : but a 
careful comparison with his description (his figure is somewhat rude and 
incorrect) has satisfied me of its identity ; the only difference being in 
the number of volutions, which in my specimens are 4 or 42 instead of 
6, and inthe aperture being twice as long, instead of “‘ un peu plus 
“« long que le sommet.”” It occurs mixed with Melampus equalis and 
exiguus, but in far greater profusion, under stones upon the beach, on the 
north side of Pta. Sad Laurenco; the eastern point of Madeira. 
That it truly belongs to the Pectinibranchia has never been doubted, 
and is indeed beyond all question. From a number of experiments, 
conducted simultaneously, and witha similar view to those above recorded 
of Melampus, upon specimens brought from the same spots and found 
under the same stones with Melampodes, I shall only select the following. 
Experiment 14. 
July 19. Two specimens of Pedipes afra inclosed in separate bags, 
and each immersed in a glass of sea-water. 
— 20. Both alive and healthy. 
—— 21. One quite lively, the other sickly and retracted. Water 
changed with both. 
