5 
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CONCHIFERA. 
Shell always bivalve , wholly or partly covering the Animal ; sometimes free, sometimes 
fixed: the valves mostly joined at the margin by a hinge or ligament. The shell is 
sometimes enlarged by testaceous, accessory pieces, not belonging to the valves. 
Thi 
S Class is divided into Two Orders, viz. Conchifera Bimusculosa, and Conchifera 
Unimusculosa. 
ORDER I CONCHIFERA BIMUSCULOSA. 
THE shell presents, in the interior, two separate and lateral muscular impressions : this 
order is divided into Four Sections, viz. C. crassipeda, C. tenuipeda, C. lamellipeda, and 
C. ambigua or the Chamacea 
SECTION I CONCHIFERA CRASSIPEDA. 
Shell gaping at the sides when shut. 
This section contains Four Families Tubicolaria, Pholadaria, Solenacea, and Myaria. 
TUBICOLARIA 6 Genera. 
Aspergillum. — Sheath tubular, testaceous, gradually attenuating to the anterior end, 
which is open ; the other extremity larger, and club-shaped ; having two valves 
incrusted on one side of the club. The disk at the end of the club, convex, and 
perforated with subtubular holes, having a fissure in the centre. 
Plate II. Fig. 5. A. Javanum. (Serpula penis. — Linn.) [Mrs. Mawe’s Cabinet.] 
6. Front view of the disk. 
Clavagella. — Sheath tubular, testaceous; the anterior end attenuated and open, the 
posterior club-shaped, ovate, and rather compressed with spinous tubes ; one valve 
fixed in the side of the club, the other free in the tube. 
Plate II. Fig. 7. (a) C. aperta. (Sowerby.) [British Museum.] 
A (6) The free valve. 
