BYSSUS. 15 
BULINUS. Brug. Fam. Colimacea, Lam.  Limacinea, Bi. 
Descr. Oval or oblong, light, covered with a thin epidermis ; 
spire obtuse, variable in length and in the number of whorls, 
which are generally few; aperture wide, oval, rounded anteri- 
orly; outer lip simple, reflected, joining the columella, without 
an emargination; inner lip reflected over part of the body 
whorl. Hab. Land, East Indies, Europe, &c. Obs. The genus 
Bulinus forms part of the genus Heuix of De Ferussac, and is 
designated the sub-genus Cochlostyla. Known from Achatina 
by not having the notch at the junction of the inner and outer 
lips. The reproduction of the animal is by means of eggs, 
which are as firm and opaque as those of birds. 
BULLA. <Auct. Fam. Bulléens, Lam. Akera, Bl. Deser. 
Generally thin, smooth, oval, oblong or cylindrical, more or less 
convolute, spire short, depressed, or hidden by the last whorl; 
aperture long, wide anteriorly, gradually narrowing towards the 
Spire; outer lip thin, inner lip spread over a part of the last 
whorl. Cbs, The shells composing this genus are very variable 
inform. The light horny species, with an elastic lip, is called 
Akera, fig. 247. The more decidedly convolute species which 
cover the spire by the volution, are the Atys. Montf. B. Nau- 
cum, fig. 250. B. Lignaria, fig. 251, is Scaphander of some 
authors. The light, thin species, with extremely wide aperture, 
fig. 248, is Bulleea Aperta, Lam. The genus Bullinula of Dr. 
Beck consists of those species which have more produced spires, 
fig. 253. The Bulle are marine, and inhabit all climates. 
The fossil species occur in tertiary beds. 
BULUEENS. Lam. A family belonging to the first section of 
Lamarck’s order, Gasteropoda, containing the genera Akera, 
Bulla and Bullea. 
BULLI'NULA. Beck. Species of Bulla, with produced spires, 
fig. 253. 
BYSSOARCA. (Byssus and Arca.) Fam. Arcacea, Lam. A genus 
of bivalve shells, composed of the Anca Noe, and several otherspe- 
cies, separated from the genus Arca, on account of their shells 
being attached by means of a byssus passing through an hiatus, 
which may be observed in the ventral margins, B. Noe, fig. 132. 
BYSSOMY’A. Cuv. (Byssus and Mya.) De Blainville states, 
that although the shell of this proposed genus resembles Saxi- 
cava, the animal is sufficiently different to justify the separation. 
BYSSUS. (Bucoos, byssus, ancient name for linen.) The ten- 
dinous fibres, by which some shells are in a manner anchored or 
moored to submarine substances. A fine instance of this is seen in 
the Pinne, whichare like large muscles, and throw outa large full 
bunch of these silky fibres, of which gloves have been made: there 
isa pair to be seen at the British Museum. The Byssusis peculiar 
tobivalve shells, such as Muscles, Hammer Oysters, Arca 
Noe, &c. 
