32 
AMEEICAN JOUE^’'AL 
B. [Liriola.) 
Shell thin, horny ; smooth, or furnished with fine radiating 
lines, which do not interrupt thè margin. Apex marginai or 
siibmarginal, twisted to thè left of thè median line in most of 
thè species. The gill passes behind thè heart and lung. The 
jaw is simple and arcuate. The rhachidian tooth is moderate, 
with a simple pointed cusp. The inner laterals are long, narrow 
and strongly bidentate. The outor laterals are broad and tri- 
dentate with short cusps. 
This section is typified by S. tliersites^ Cpr., and would in- 
clude S. lateralis, Gld., S. redemiculum, Rve., S. Macgillivrayi, 
Rve., S. Lessarli, Blainv., and all thè similar species, such as S. 
tristensis, S. lineolata and others from thè South American 
coast. The species are more numerous in thè tempei’ate zone, 
though not confined to it. 
If it be considered desirable to give a name to this group, 
Liriola might be used in a restricted sense to indicate it. 
The following species belongs to thè first section : 
SlPHONARIA ALTERNATA, Say. 
Patella alternata, Say, Journ. Phil. Acad. Sci. voi. v, p. 
215, Feb., 1826. 
Siphonaria alternata, Say, Am. Conch. part iv, pi. 38, 1832. 
Binney’s Say’s Works, pp. 124, 192, pi. 38. Binney L. 
and F. W. Shells of N. Am. part ii, p. 153, fig. 254. 
Chenu, 50, pi. xiii, fig. 3. 
Shell conical, with more or less elevated, unequal ribs, thirty 
or more in number. Apex subcentrai, recurved obliquely, thè 
tip pointing in a nearly parallel direction with thè longitudinal 
axis of thè shell, and acute. Color brown, radiated with white ; 
base ovai. Length three-tenths of an indi. 
Say’s figure of this species in Binney’s reprint is represented 
as with too few ribs and too smooth interspaces. The wood-cut 
copy in thè L. and F. W. Shells of IST. A. is also very poor. 
The external appearance of thè animai is much like thè next 
species. The mantle edge is brown, thick and somewhat corru- 
gated. The remainder is livid siate color. The lobe which 
closes thè pulmonary opening is large and thin, gray and edged 
with brown. There were no eyes visible, yet they probably exist 
and are very minute. The anatomy resembles that of thè next 
species, except that thè penis is larger in proportion to thè size 
of thè animai. 
The jaw is simple and arcuated. The centrai tooth is very 
slender ; thè cusp has a simple point. The inner laterals bave a 
