AND HABITS OF MARINE TESTACEOUS MOLLUSCA. 
511 
concealed under the insertion of the funnel-shaped muscle. A highly mag- 
nified view of this part of the tongue is given in fig. 18. 
Reverting to the state of the parts in fig. 16, we divide the transverse bands 
of the base, and thus display the internal parts as in fig. 19. The sheath of the 
tongue is now fully exposed, with four pairs of oblique muscles inserted into 
it ; of which one pair, i, take a direction backward, the others, Jc , k, forward. 
Finally, in fig. 20. all these muscles are cut, and the tongue itself thrown 
aside. A deeper-seated pair of broad oblique muscles, l, and the insertions of 
the longitudinal ones are thus brought into view ; while the internal structure 
of the base itself, with its muscular columns, and the cartilage with which the 
external ones are tipped, may now be conveniently examined. 
The trunk of Buccinum lapillus must not be supposed to differ from that of 
undatum only in its size. It is essentially distinct in many points ; but I 
shall not attempt a description on the accuracy of which I could place no re- 
liance. The trunk of Murex echinatus appears to be of the same kind ; pre- 
senting but a small mass of muscles at the very extremity of the tube. Some 
of the large tropical Murices will probably enable us to determine the anatomy 
of this variety. In the trunk of Buccinum reticulation, we may trace without 
difficulty a very close conformity to the type of undatum,, though the diameter 
of its muscular apparatus does not exceed that of a small pin. 
There is another branch of the subject, into the details of which I shall not 
enter at present, but whose importance may claim a brief notice. In the 
modern systems of conchology, a beaked shell is considered to indicate a carni- 
vorous animal ; while an entire aperture is regarded as an equally unexception- 
able mark of a herbivorous one. The first, I believe, is not to be disputed. 
There appears indeed no necessary relation between a respiratory tube and a 
boring trunk ; and it may be curious to inquire why some of the carnivorous 
trachelipodes, Buccinum undatum and reticulatum, Cyproea, and others, carry 
their respiratory tube projected in an arch ; while in Buccinum lapillus and 
Murex, it is lodged in a channeled beak : but there can be little doubt that 
all the beaked spi rival ves are predatory. The opposite conclusion however 
is quite untenable; and the well-known example of lanthina would alone be 
sufficient to overturn it. Although this molluscum cannot pierce shells, as 
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