. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. Fig. 41. TROCHUS CONCAVUS, Fig. 42. TROCHUS IRIS. Another variety is remarka- ble for a deep excavation at the base of the columella, resem- bling an umbilicus, and a pro- jection of the circumference, as is seen in the figure of the con- cave trochiis {Jig. 41), which inhabits the Indian Seas, and is considered rare. There are other species, without an umbi- licus, conical with a very oblique base; the aperture large, slightly angular» the columella twisted, and forming a kind of tooth at its termination. Such
. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. Fig. 41. TROCHUS CONCAVUS, Fig. 42. TROCHUS IRIS. Another variety is remarka- ble for a deep excavation at the base of the columella, resem- bling an umbilicus, and a pro- jection of the circumference, as is seen in the figure of the con- cave trochiis {Jig. 41), which inhabits the Indian Seas, and is considered rare. There are other species, without an umbi- licus, conical with a very oblique base; the aperture large, slightly angular» the columella twisted, and forming a kind of tooth at its termination. Such is the rainbow trochus {fg. 42), the nacre of which is a beautiful golden green, with very brilliant reflections of red. 31. The tribe of Turbo comprises all the pecti- nibranch gasteropods which have a completely and regularly turbinated shell, terminated by an entirely round aper- ture In it we range the turbo properly so called, delphinula, turri- tella, scalaria, cyclostoma, valvata, &c. {fg. 43). 32„ The Turbos properly so called are recognised by their round or oval thick shell, in which the ap- erture is completed within by the whorl of the spire next to the last. These mollusks have two loner ten- o tacles, which, at their base, externally, support the pedunculated eyes; on the sides of the foot we remark membranous wings, sometimes simple,sometimes fringed or furnished with one or two filaments; and their operculum is sometimes horny, at others calcareous, or extremely thick.— Among the varieties of this genus is the Tvrho Pica {fig. 44), which inhabits the 31, What are the characters of the tribe of Turbo ? (Turbo is a Latin word, meaning a whirling or twisting.) 32 What are the characters of the Turbo properly so called?. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ruschenberger, W. S
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectmollusks, bookyear184
