1833.] Note on the Genus Spiraculum. 591 
Haliotis being furnished with tubes or spiracles well known as so many 
passages for a syphon; while Stomatella and Stomatia, which in other 
respects so much resemble it, have none. 
And yet a mere breathing hole would scarcely require to be protected 
by a tubular process. But there may be attached to the neck of the 
animal of Spiraculum, an apparatus similar to that described by La- 
MARCK as possessed by the genus Valvata of his Péristomiens ;—“ un filet 
branchial et tentaculiforme au cété droit du cou, et quelque-fois une 
branchie en plumet et contractile, qu’il fait sailler hors de sa cavité :”’ 
or a projecting syphon, such as carries on the respiration of the se- 
cond section of the Trachelipoda. Thus there would be an animal 
breathing air yet furnished with the apparatus, or a modification of the 
apparatus of one inhabiting and breathing only water, and consequent- 
ly occupying an intermediate place in the chain of affinity, and form- 
ing an inosculation between the two. If so Lamarck might have 
adduced it, had it been known to him, as another fact, strongly 
confirmative of his celebrated idea of the gradual perfection of the 
animal form. His remarks on the subject are so apposite, 
that they deserve to be quoted entire. ‘‘ A mesure que,” says 
Lamarck, ‘‘ les animaux se repandirent partout de proche en proche, 
il parait que ceux des trachelipodes fluviatiles que habitérent les 
eaux qui ont peu de profondeur, comme celles des petites riviéres des 
étangs, et des marais, que sont exposées a tarir, furent souvent réduits 
a vivre dans une vase plus au moins desséchée. IIs se trouverent donc 
forcés a s’habituer a. l’air, a le respirer. Or cette habitude ayant modifié 
leurs branchies, comme celles des colimacés, est devenu pour eux une 
nécessite ; en sorte que quoique vivant dans l’eau ils sont maintenant 
obligés de venir de temps en temps a sa surface pour y respirer lair libre.” 
If any change of this kind ever did take place, it may perhaps be 
found at some future time, when physiological investigations are better 
understood than at present, that these animals are able to breathe both 
air and water; and further, should the above conjecture as to the re- 
spiratory apparatus of Spiraculum prove to be correct, there will be ano- 
ther link of union between the second section of Colimaceés and the 
Péristomiens beside that of the Lymnéens. 
Genus, Spiraculum. Species, Hispidum. 
Specific Characters. Animal unknown. 
Shell white, subdiaphonous, upper surface of the body whorl 
slightly patched with rufous. Epidermis dark-brown, covered with 
short bristly hairs, which at the outer and under side of the whorl are 
placed thickly together, giving an appearance to the shell of its being 
zoned with three narrow dark lines ; whorls five, breathing tube one line 
