No. 2.] AJVATOMV OF A SPECIES OF PLATVASPIS. 6 1 



ridges which border these compartments is shown in the cam- 

 era lucida drawing of the ventral surface. This number of 

 compartments is different from that given by authors for 

 P. lenou'i, where there are 25 compartments, 18 in the periph- 

 eral series, and only 7 in the median row, in place of 20 

 in the peripheral and 9 in the median row, as here. I have, 

 however, not determined how constant the plan of this sub- 

 division of the ventral sucker is, but I have found the number 

 given in my figure in about twenty cases. 



Internal Anatomy. 



The animal is covered with the usual trematode body wall, 

 consisting of a thin and delicate cuticle, beneath which, in sec- 

 tions, the ends of muscle fibers are recognizable. Internally 



Fig. 4. 



Fig. 5. 



Fig. 4. —Transverse section, passing through the eyes, level Oc. in Fig. i, No. 12 of series 



(camera lucida). 

 Fig. 5. —Transverse section, No. 31 of series. The left of the section is the right side of 



the animal (camera lucida). 



the inter-spaces between the organs are filled in with the usual 

 parenchymatous tissue. This is subdivided into that of the 

 body and that of the foot by a transverse diaphragm, as seen 

 in Fig. 6. The alimentary and excretory systems lie wholly 

 dorsal to this structure, as well as the terminal ducts of the 

 reproductive system, while the gonads themselves, and the 

 vitellaria, are wholly ventral to the diaphragm. 



The alimentary system begins with a widely dilatable funnel- 

 shaped "pre-pharynx," surrounded by the extremely mobile and 



