Introduction to Animal Morphology. 207 



The intestine is straight, attached medio-dorsally 

 by a longitudinal band to the body wall, medio-ven- 

 trally by interrupted mesenteric threads, traversing 

 which, close to the ganglion, is a vessel. The anus is 

 ventral, near the hollow tail, which is divided by a 

 partition, and in which spermatozoa form from proto- 

 plasmic masses detached from its walls, and escape by 

 lateral slits, to which sometimes seminal vesicles are 

 appended. There is a saccular ovary on each side of 

 the intestine, opening beside the anus. An oval, 

 ventral nerve-ganglion (= the cephalic ganglion of 

 X< >matodes) sends backwards a pair of lateral branches, 

 and forwards another pair which unite pre-orally in a 

 hexagonal ganglion. This sends off lateral branches 

 to the conical tentacles when they exist (S. cepha- 

 loptera , and two anterior branches to the pair of eyes, 

 which consist of radially arranged cry stal cones on a 

 >us layer and mass of pigment. 



Sometimes a dorsal, wheel-like disc exists, placed 

 like a saddle. The non-ciliated embryos are directly 



eloped, the egg passing through a gastrula stage. 

 The one genus Sagitta is found in the Mediterranean 

 and Atlantic. Chaetosoma is probably one of its 

 nearest allies. They have been regarded as Verte- 

 brates ( Mt- issuer , or as Molluscs (Forbes). 



vss 10. ENTEROPNEUSTI //Y;v///w// ; worm- 

 like,, brittle, contractile, dioecious animals, flattened, 

 Liar-like swelling in front, and ronsist- 



iral, flattened parts, and a middle annu- 

 ion showing traces of metameric growth. 



ly ciliated, protoplasmic rutis secretes much 

 mucus 1)\- its unicellular glamN. Th<- HIUM -ul.ir coat 



i.idinal bundlrsoi iii 



