JAPANESE LAXD LEECHES. 293 



one ganglia in the ventral chain, not counting the nerve-mass at the 

 fore and hind extremities. Analogous to all other genera of leeches 

 hitherto investigated, the œsophageal ganglionic mass is composed of 

 5 ganglia, that are clearly distinguishable, and some groups of gang- 

 lionic cells representing perhaps the rest of another ganglion. The 

 acetabular nervous mass is made up of 7 ganglia. Adding these num- 

 bers together, we have the total of 33, a number that holds good for 

 every member of the Gnatlwhdellidce as well as of lüiijnchohdellidce. 

 Thus Orohdella agrees with all other leeches in regard to the funda- 

 mental plan of the nervous system and consequently to the number 

 of the somites. 



Anatowij. 



Integument. The body is enveloped in a thin layer of chitinous 

 substance, the cuticle, under which lies a single layer of colunuiar 

 cells, the epidermis. There are many unicellular glands scattered 

 over the whole surface, some of them lying much deeper than 

 the rest. Among the columnar cells of the epidermis, or passing 

 through them, are found networks of capillaries, that run parallel to 

 the external surface of the animal, in the same manner as indicated in 

 the tigiu-es of the medicinal leech by Prof. Lankester. Within the 

 clitellar region the number of deep-lying glands is decidely greater 

 thîin at other localities of the body. 



MoutM-cantij. As these leeches are destitute of toothed jaws, the 

 mouth leads directly into the mouth cavity, which forms an enormous 

 space reaching behind the XIII somites (Pi. XXX, Fig. 3). In cross 

 sections, this cavity has a triangular outline (PI. XXX, Fig. 4) and 

 shows, besides, some small shallow grooves on each side. Circular 

 nuiscle-fibres are pretty well developed around the cavity. The 

 salivary gland opens mostly into the anterior portion of this cavity, 



