BRACHIOPODA. 
il 
and nearly entirely cartilaginous. The family consists only of a 
single genus. Lingula. 
Order V. Rudistes. 
This Order has been placed by modern authors with the Bra- 
chiopoda : the proofs of its belonging to this family are not very 
evident ; but as there is no other to which they appear to be more 
nearly allied, they may as well be retained in this position. 
Lamarck, Cuvier, Ferussac, and some other authors have re- 
garded some of the genera as belonging to Cephalopoda, and 
others as Bivalves (Conchifera). Deshayes regards them as more 
neai-ly allied to Chama, the character of the family having been 
lost by the destruction of the inner coat of the shell during the 
fossilization of the specimen. 
M. d’Orbigny has properly united them into one group under 
the name of Irregular Brachiopods or Rudistes, but he includes 
with them the genus Crania, which is a true Brachiopod. 
They form three very distinct families. 
Fam. 1. Radiolitidce. 
The lower valves more or less elongate-conical, fixed; the 
upper valve conical or spiral, free ; the texture of the lower valve 
cellular or fibrous. 
The Radiolites has the upper valve flat or conical and cap-like. 
The Caprina, D’Orb., has a spiral and produced upper valve. 
The first of these genera has had many names applied to it, but 
that given by Lamarck has the priority. It has been called 
Sphmrulites, Ostracites and Acardo, and the cast of the interior 
cavity has been considered as a genus, under the name of Biros- 
tris and lodamia. 
Fam. 2. Hippuritidm. 
The lower valve is elongate, tapering sub-cyhndrical, of a solid 
laminated texture ; the upper valve is nearly flat, and pierced 
with pecuhar pores radiating to the circumference with branches 
diverging to the upper surface. 
This family contains only a single genus, Hippurites, Lamarck, 
which has also had many other names applied to it, as Cornu- 
copia, Orthoceratites, BatoKtes (or Batholites), Raphanister, and 
Bitubulites. 
Fam. 3. Caprotinidm. 
The lower or fixed valve is conical and spirally twisted, and 
marked internally with prominent ridges or transverse septa ; the 
dorsal or free valve is oblique or sph-al. They differ from Ca- 
prina in the valves not being of a cellular or fibrous texture. 
This family contains two genera ; — 
1. Caprotina, D’Orb., which has the cavity of the shell merely 
marked with internal ridges. 
