Fig. 5. 
EXPLANATION OF PLATES. 843 
belts; %, the gill; /, the heart; 7, dorsal folds (endostyle ?) ; t, 
languet ; }, (in B) the cerebral ganglion. 
Ascidia (Cynthia) Momus, p. 707 ; after Savieny Mémoires, 1. 
Pl. vr. fig. 1. A, respiratory aperture ; B, cloacal aperture ; ¢,¢,¢, 
outer covering, of which one half is removed in order to shew 
the internal envelop d (the mantle); e, muscular fibres on the 
mantle. 
Figs. 6, 7. Fig. 6. Lingula anatina LaM., p. 721; after Cuvier Ann. du 
Fig. 
bo 
Mus. 1. fig. 6. The animal in its shell with the peduncle B. 
Fig. 7. The animal removed from the shell, one of the laminz 
of the mantle thrown upwards ; a, the cerebral ganglion, accord- 
ing to Cuvirr; 8, mouth ; ¢,¢, the two arms ; d,d, d,d, pectinated 
gill-folds on the mantle. 
The animal of an Anodonta in the shell, of which the right valve 
is removed, as an example of Lamellibranchiates, pp. 723, 724; 
comp. Pl. 15, fig. 1; a, shell (left valve from the inside) ; 8, 6, 
the two laminz of the mantle ; ¢, c, outermost gills ; d, e, inner 
gills; g, the flat ventral dise projecting between the gills ; * ten- 
tacles round the mouth, those of the right side alone are seen ; 
+ mouth ; A, anterior adductor muscle; 0’, 6’, the posterior 
border of the mantle beset with fringe-like appendages. 
Puate XV. Mo..uscs. 
A transverse section of Anodonta anatina, schematic after NEv- 
wyteR, Neue Denkschr. der allg. Schweizer. Gesellsch. fiir die 
gesamumten N aturwissenschaften, Bd. v1. 1842, Tab. 1; a, a, b, 6, 
and g, as in fig. 8 of the preceding plate; ¢, external laminz of 
the outer gills with the dorsal side attached to the mantle ; d, 
internal lamina of the outer gill ; e, external ; J, internal lamina 
of the inner gill; h, heart, traversed in the middle by the 
rectum. 
Solen legumen L., p. 754 ; after Powr Test. wtr. Sicil. 1. Tab. Xt. 
fig. 15 ; A, the foot projecting at the anterior extremity of the 
shell ; B, c, the two tubes (traches) coming into view from the 
shell behind. 
Clio borealis Guen., p. 775; after Escuricut Anat. Unters. 
Tab. 1. fig. 3; the animal is represented from the ventral surface ; 
a, a, fin-like appendages ; 4, 6, conical appendages ; ¢,c, tentacles 
of the head ; d, everted penis with a vesicle d’ at the base. 
