10 
BRACHIOPODA. 
t/Hcifes, Defrance?; Tn^'owosemwSjKcEiiig; ilAywc^ora, Dalman ; 
Pygope, Link ; Delthyridaa, M‘Coy ; Pentamerus, Sowerby. 
Order IV. Sarcicobrachia. 
The oral arms fleshy to the base and without any shelly sup- 
port ; the lower valve without any processes on the hinge-margin 
or disc, or except sometimes a shght medial longitudinal elevation. 
Fam. 1. Productidee 
consists entirely of fossil species, some much resembling those 
of the former family, but the shells are generally spinose ; they 
are only attached to marine bodies by the surface of the ventral 
valve, as the genera Productus, Sow. ; Strophalosia, King ; Cho- 
netes, Fischer; Leptmna and Orthis, Dalman; Strophomena, 
Rafinesque ; and Calceola, Lamk. This family comprises Mr. 
King’s ProductidcB, Strophomenida and Calceolide. 
Fam. 2. Craniada. 
Nearly allied to the last, but the upper valve is simply conic 
like Patella, and the animal is attached by the outer surface of 
the ventral valve. 
The animal has been figured by Muller, Poli and others. It 
includes the recent genus Crania of Retzius, including the Or- 
bicula of Lamarck, Criopus of Poli. The lower valve of the only 
recent species I am acquainted with varies greatly in thickness 
and form according to the position and habitation of the animal. 
This animal in many particulars is alhed to ThecidceadcB. 
Fam. 3. Discinida. 
The upper valve is conical and patelloid, the lower orbicular, 
and is attached to marine bodies by a short tendinous peduncle, 
which passes out through a slit in the hinder part of the disc of 
the ventral valve. 
The animal of this genus has been described by Mr, Owen 
under the name of Orhicula, Mr. G. B. Sowerby having some 
years ago confounded this shell nith that genus, which has caused 
confusion, which has existed to this day. The shell was first de- 
scribed by Schumacher as a section of the genus Crania. Mr. 
King, probably misled by this mistake, does not include it in his 
arrangement. This shell is peculiar, for being homy rather than 
a shell texture, it is flexible when moist. 
Fam. 4. Lingulidts. 
The valves are nearly equal elongate, and supported by a thick 
peduncle which comes out between the beaks of the two valves. 
The shells are covered with a horny periostraca, and in some 
species the shelly matter is so very thin that the shells are flexible 
