142 
LECTURE X. 
with their arms or tentacula, and to absorb by 
means of their mouth or central orifice. They are 
probably viviparous animals; they are in general 
called by the popular title of sea-blubbers, and 
are sometimes so very numerous as to float by 
thousands on the surface of particular parts of the 
sea. 
Another very singular genus is that of Holo^ 
thuria, of which the characters are, an oblong, 
nayant'or floating body, furnished at one extre- 
mity with several arms, feelers, or tentacula, sur- 
rounding the mouth or opening. I shall here ob- 
serve, once for all, that many of the Linn^ean ge- 
nera of the Mollusca are capable of considerable 
improvement, and that he has somewhat too fre- 
quently associated under one genus, animals not 
sufficiently resembling each other in habit or ge- 
neral appearance. The most common perhaps of 
the European species of the present genus is the 
Ilolothuria iremida ; an animal of a lengthened, 
cylindric form, of a purplish-red colour, and beset 
on all sides with very numerous soft tubercles of 
dilferent sizes; and furnished at its upper end, 
round the mouth, with numerous short but cu- 
