201 
side ; foot short, oval, with an anterior marginal groove ; head with 
a proboscis, depressed ; tentacula remote, with the eyes on their 
middle, beyond which they are slender ; mouth terminal, vertical, 
without labial tooth and with a very small tongue j a long and nar- 
row branchia. 
Ohs. Brugu^ire adopted the name of this genus from Adanson, 
who says, that Fabius Columna used the word to designate one of 
the species. The following is the descriptive appellation of the 
latter, Buccinum tuberosum Cerithiumparvum.^^ All the species 
which Adanson referred to it are correctly placed, with the ex- 
ception of the Ligar, ( Turritella terehra, L.) and the Mesal, both 
of which he was aware differ generically from the others. He thus 
describes the operculum of G. radula, L., and his figure corres- 
ponds in character, opercule exactement orbiculaire, cartila- 
gineux, fort mince, brun transparent et marque de cinq sillons 
circulaires concentriques,” but Blainville says it is subspiral. 
They are marine, and crawl upon the mud, feeding upon small 
animals. 
These shells are generally elongated cones, beautifully decorated 
with regular series and bands of granules, tubercles and other sym- 
metrical protuberances. Linne placed the species known to him 
in the very different genera Murex, TrocTms and Stromhus. Blain- 
ville includes, as subgenera, Pyrena, Lam., Potamides, Brong., 
PyrazaSj Montf., Nerinej Def., and TripTiora, Desh. The aper- 
ture of the two latter have a complicated appearance, and the 
others are altogether destitute of canal. 
Numerous recent and still more fossil species have been described, 
chiefly by Lamarck, who remarks, that the more our collections 
become enriched, the more difficulty attends the determination of 
of genera, and particularly of species ; the vacancies which we sup- 
posed to be natural limits become proportionally filled up. The 
difficulty he experienced in fixing the character of each species 
of CeritJiium led him to the conclusion, that it is principally 
in this genus that this fact is the most evidently shown, because 
the collections abound in these shells. The study of these shells is 
very important to the geologist in his attempts to ascertain the 
changes that have taken place in the surface of the globe. 
Cerithium muscarum. — Specific character. White, with 
costae, transverse striae and series of brown spots. 
16 
