172 



ZOOLOGY 



groove, whose other side is formed by a lip which also mas 

 round the edge of the lophophore (Fig. 109). The tentacles are 

 partially ciliated as well as grooved, and any particles of 

 food they come in contact with are carried down the 

 groove to the mouth, which opens in its posterior median line. 

 In other genera the lophophore stands out from the surface of 

 the body and becomes curiously coiled and rolled up, as in 

 Waldheimia (Fig. Ill), in which animal it is supported by a 

 calcareous loop. 



The mouth is a transverse slit leading into a short 

 oesophagus; this is attached by mesenteric strands to the 



Fig. 109. — Transverse section through the middle of Argiope neapolUana. The 

 section includes the posterior limit of the lophophore, but is anterior to the 

 brood pouches. 



1. Stomach. 



2. Gastroparietal bands. 



3. Ovary in dorsal shell. 

 3'. Ovary in ventral shell. 



4. Dorsal adjuster muscle. 



5. Occlusor muscle. 



6. Left mesentery ; posteriorly this 



fuses with the right to form a 

 single mesentery. 



7. Ventral shell. 



8. Vascular canal in shell. 



9. Canal at base of lophophore, which 



sends a branch into each tentacle. 



10. Lip forming with the tentacles a 



groove. 



11. Dorsal shell. 



end of the median projection of the dorsal shell, and it opens 

 directly into the globular stomach. On each side of the aliment- 

 ary canal is the liver, composed of six or seven thick tubules, 

 which unite and open into the stomach by a broad mouth. 

 The lumen of the liver is often full of secretion, it is lined by 

 vacuolated cells. The stomach opens behind into a short intes- 

 tine which has no anus, and which, like the rest of the aliment- 



