bu 
THE LAMELLIBRANCHIA 2 
WN 
= 
in adult forms, viz. three in certain Nuculidae, in Chama, and 
Spondylus ; four in Arca; five in Pectunculus, Phiiobrya, and Pecten ; 
and as many as twelve in Mytilus. The lumen of the hepatic 
glands may be of considerable size, and form part of the digestive 
and absorptive cavity. In certain Lucinidae (Montacuta, Axinus, 
Fig. 238) the hepatic glands, together with the overlying gonads, 
project into the pallial cavity in the form of arborescent tufts. 
The intestine almost always arises from the ventral side dof the 
stomach, and is sometimes provided with a valve at its origin 
(Pinna). It is short and rectilinear or scarcely coiled in Solenomya, 
in sundry Filibranchia such as Arca, Pectunculus, Limopsis, Philobrya 
(Fig. 234), Anomia, and in the Septibranchia (Fig. 251, in); but 
Fie. 201. 
Median sagittal section of the anterior part of the digestive tract of Donaz. a.l, anterior 
lip; cae, caecum; cr.s, crystalline style; cu, stomachal cuticle; in, intestine; m, mouth ; 
oe, oesophagus ; p.l, posterior lip; st, stomach. (After Barrois.) 
more usually, as the Lammellibranchs are nearly all herbivorous, it 
describes a certain number of convolutions in the viscero-pedal mass 
(Fig. 242, al). These may vary from one to a dozen in number, 
and sometimes they are confined to one side of the body ; in the 
Nuculidae and Ledidae, for example, they are on the right side. 
The intestine is ciliated throughout its whole length, and its rectal 
portion is generally provided with an internal longitudinal ridge. 
In Nucula (Fig. 204, XIV), Arca, and Anomia the rectum passes 
ventrad of the ventricle of the heart, as it does in Amphineura ; 
but it traverses the ventricle, in rhipidoglossate fashion, in the 
majority of Lammellibranchia. But in Malletia, Avicula, most 
species of Ostraca, Miilleria, and Teredo (Fig. 195) it is dorsad 
of the heart. Finally, the rectum always passes over the dorsal 
side of the posterior adductor muscle, and ends behind it in 
