SYSTEMATIC ARRANGEMENT OF THE 
FIGURES. 
[CONTINUED FROM VOL. IV. | 
Class I. CONCHIFERA. 
Animal having the mouth placed between the gills. They and 
the body enclosed between the two leaves of the mantle, which are 
covered with two shelly valves. The valves are on the side of the 
animal, and united behind and above by a ligament and cartilage. 
Subclass I. SIPHONOPHORA. 
Mantle leaves connected, with two siphonal openings behind. 
There is sometimes a minute fourth aperture, with an internal 
valvular protuberance on the mantle under the siphons. 
Order I. VENERACEA. 
Mantle with two more or less elongated siphonal openings. Gills 
short, not produced into the inhalent or lower siphon. Siphons 
under the hinder adductor muscle often more or less separate. 
I. Foot compressed, generally without any byssal groove. Animal 
crawling. 
1. Cardinal teeth diverging. Central tooth bifid. Cartilage of 
hinge external, marginal. 
A. Siphons more or less united, short. 
Fam. 1. Veneride. 
Mantle lobes free. Hinder lateral tooth compressed, and form- 
ing a part of the margin of the shell. 
* Foot lunate, inferior. Siphons united. Shell and body orbicular. 
1. ARTEMIs. 
1. A. Lupinus, t. 313. f. 1. 
2 AS lincta, ita oles de 2s 
3. A. exoleta, t. 313. f. 3. 
** Foot lanceolate, anterior. Siphons partly united. Shell ovate, 
triangular or oblong. 
a. Anterior lateral tooth distinct. Cardinal teeth triangular. 
Shell ovate. 
+ Hinder cardinal tooth cross-grooved or torn. 
1. MERETRIX, 
