The anatomy of Lottia gigantea Gray. 59 



7) There is a small forechamber or proventriculus to the stomach. 



8) The liver empties by a single large hepatic duct into the 

 proximal end of the stomach. 



9) The nephridia are very unequal in size, the left being a tiny 

 sac on the left side of the rectum. The right is large, surrounds the 

 visceral mass, and ends in a cul-de-sac behind the pericardium. 



10) Both nephridia are in communication with the pericardium 

 by long canals, which are really diverticula of the pericardium. Only 

 that small portion within the papillae, at the nephridial ends of the 

 ducts, is ciUated. 



11) The gonad is large and occupies the ventral portion of the 

 cavity containing the viscera. It lies within the coelom or secondary 

 body cavity and is in communication with the anterior part of the 

 right nephridium by a slender duct. 



12) The heart consists of an auricle and ventricle, with a two- 

 lipped valve between them. 



13) The circulation is for the most part closed. Sinuses, however, 

 collect the blood in the foot, and there are also open lacunae of 

 minute size in the liver. The arterial system is extensive. The 

 mantle circulation is very well developed, and receives blood from the 

 kidneys, foot and gonad. Over the nephridia there is present a highly 

 developed vein-net. The mantle discharges its blood directly into the 

 auricle. 



14) There is a simple ctenidium, on the left side, which receives 

 blood from the right kidney. 



15) The mantle is an important auxiliary respiratory organ. It 

 is provided with a cordon of lappets (interrupted in front) which first 

 appear when the animal is about 20 mm in length. The mantle edge 

 contains three sets of glands. 



16) In connection with the radula, there has been developed a 

 complicated system of buccal and radular muscles. 



17) The cerebral ganglia supply nerves chiefly to the tentacles, 

 eyes, otocysts and lips. 



18) Two well developed labial gangHa are present, and supply the 

 palps with nerves, besides giving rise to the stomatogastric and sub- 

 radular commissures. 



19) There are two small subradular ganglia, situated behind the 

 labial ganglia on the subradular pocket of the oral cavity. These 

 ganglia send nerves primarily to the subradular organ. They are united 



