9230 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
because we know little more of it than our predecessors. We believe that 
two or three Trichotropides have been discovered, and it now remains for 
Professor Owen, or some other learned anatomist, to determine their true 
physiological character. 
The shell of Trichotropis may be described as being thin, turbinated, 
and covered with a thick, horny epidermis ; the spire is somewhat raised, 
and the whorls are generally more or less carinated, the epidermis on the 
carine forming a row of fine bristles, which extend throughout, and are 
mostly regular and erect ; the last whorl is slightly canaliculated at the 
base, and forms in all instances a rather large umbilicus ; the aperture is 
triangularly ovate, and the length of it is equal to, if not exceeding, that 
of the spire ; the columella, which is arched, ends in a somewhat obliquely- 
truncated point, and the lip is very thin and acute. The operculum, which 
has a lateral nucleus, is composed of a close series of elliptical lamine. 
Examples. 
Pl. CCLXV. Fig. 1 and 2. 
TRICHOTROPIS BICARINATA, Broderip and Sowerby, Zoological Journal, 
vol. iv. p. 374. pl. 11. f. 4 to 8. 
Trichotropis Soverbiensis (?), Lesson. 
Pl. CCLXV. Fig. 3. 
TRICHOTROPIS UNICARINATA, Sowerby, Genera of Shells, No. 42. 
MAGILUS, De Montford. 
Testa alba, solidissima, in spiram ovatam convoluta, anfractibus tribus aut 
quatuor, ultimo in tubum plus minusve elongatum, vel flexuosum, 
vel undato-rectum porrecto ; tubo in carinam infra producto, super- 
ficie rugosa, lamellata. Operculum corneum, ellipticum, in striis 
subconcentricis dispositum. 
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