MOLLUSCOIDEA — BRACHIOPODS 



i8s 



From the mouth the food passes through an oesophagus into 

 the stomach, into which from each side opens a large stomachal 

 gland which probably performs the functions of both liver and 



di. 



. sto. s.g. 



mo. cm. 



'"> ■ /I 



H 



I 



Fig. 73 h. — Terebratulina scptentrionalis. F, longitudinal vertical section through 

 entire animal ; G, H, I, young stages of the shell, looking upon the brachial valve 

 and the pedicle opening of the pedicle valve. G, earliest attached stage in the 

 growth of the shell, showing the large open delthyrium. H, a later stage. /, stage 

 showing the introduction of the radiating striae and an approach to the adult in 

 outline, cru., crura (the bases of the brachidium) ; di., diductor muscle; e.g., 

 external glands; mo., mouth; s.g., stomachal glands; sto., stomach. The size 

 of G and H are indicated by the mark within the circle, of / by the line to the right. 

 (From Morse.) 



pancreas of higher forms, thence into the intestine W'hich ter- 

 minates in a closed point, no anal opening being present (Fig. 

 73 b, F). The digestive waste, in the shape of minute pear-shaped 

 bodies, is carried out of the stomach through the oesophagus by 

 the cilia lining it, and is ejected through the mouth. The digested 

 food absorbed by the surface of the digestive tract, aided very 

 largely by the stomachal glands, passes into the body cavity 

 surrounding it. The fluid filling this body cavity is moved by 

 the cilia lining it and performs the function of the blood ; 

 thus the digested food entering it is urged into all parts of the 

 body. This body cavity, or ccelome, is continued into the 

 lophophore and its branches ; it also extends into each of the 

 mantle lobes in the form of branched canals, — pallial sinuses; 

 the impression of these upon the shell is often seen in fossil 

 forms (Fig. 85, D, E). The coelomic fluid or blood is colorless 

 and contains corpuscles. A small contractile sac posterior to the 

 stomach has been considered as possibly a heart, and radiating 

 from this are a number of vessels ; since the main blood circula- 



