32 LECTURES ON MOLLUSCA. 



The teeth in all the families thus far enumerated are formed on the 

 Whelk type, in rows of three each ; of which the central one is broad 

 and fixed, while the side ones are movable. All three are armed with 

 variously shaped hooks. In the next group of families, the lateral as 

 well as the central teeth are fixed ; and the shell always has folds on 

 the pillar. 



Family FASCIOLAKIAD^:. (Tulip-shells and Mitres.) 



This family embraces two very different looking groups of shells, of 

 which Fosciolaria and Mitra are the types. They agree however in* a 

 very peculiar dentition. The central teeth in each row are very small ; 

 but the lateral ones are long, narrow, and armed with points like a saw. 

 The tulip-shells are not very strong, generally knobbed outside, with 

 the breathing canal a little curved. They are known from Fusus by a 

 few very slight and slanting folds on the pillar,' close to the breathing 

 pipe. The Fasciolaria gigantea of the South Carolina seas is sometimes 

 two feet in length, rivaling in size the great Hemifusi of the East 

 Indies. Small specimens greatly resemble the F. princeps of the west 

 coast, but are at once distinguished by the sculpture on the operculum 

 of the latter. The group called Fulgur, which abounds on the Atlantic 

 shores of North America, with the East Indian group Tudida, were 

 formerly reckoned with the Pyrulas. Whether they have a whelk- 

 like dentition, or whether they are Fasciolarias with undeveloped plaits, 

 cannot be told till their animals have been dissected. Whether it 

 speaks well for the zeal of American naturalists that these large species, 

 which can be so easily examined, should be abundant in collections, as 

 far as the shell is concerned, but as yet undescribed from the living 

 animals, must be for others to determine. 



In LatiruSj the shell is shaped like Fusus or Pisania, but with a 

 few parallel plaits. In Peristernia these evanesce, as in Fulgur ; and 

 some species can hardly be known from Pisania. In Leucozonia, 

 there ia spine in the outer lip, as in Monoceros. The stout claw- 

 shaped operculum, which characterizes this tribe as well as the Muri- 

 cids, at once distinguishes the shell : but Lamarck's error has been 

 repeated by many authors, and even by Chenu. 



The genus Fastigiella is known only by its shell ; which seems to 

 represent the Cerites among the Fasciolarias. The plaits are obsolete. 



The Mitra group have always been great favorites. They generally 

 have slender, pointed shells, with elegant sculpture and particularly 

 brilliant painting. There are a great multitude of species, but most 

 of them are rare. They have a love for an insular life; being found 

 in great abundance in the islands of the Indian and Pacific oceans, 

 while the shores of the neighboring continents have only a few, and 

 those plain species. The Atlantic ocean is not their favorite: even 

 the choice islands of the West Indies only boasting of a few dull 

 species. The pillar lip is always strongly plaited, the top plaits being 

 the strongest. They are remarkable for doubling up their little foot 

 longitudinally, when they draw themselves in. The operculum is 

 generally absent. They have the power of emitting a very nauseous 

 odor when disturbed. Their proboscis is enormously long, out of all 



