[2 6 TELE LEECHES OF MINNESOTA 



ican species there are four pairs of conspicuous black eyes, though 

 variations in which one or both of the anterior lateral ones are absent 

 occur in about ten per cent of those studied. The anterior eyes are 

 larger than the posterior, those of the two pairs almost in contact and 

 their pigment cups situated well within somite III. The posterior 

 eyes are smaller, looking outwards and backwards from the lateral 

 faces of the posterior part of IV. 



The genital orifices are separated by a greater distance (normally 

 three and one-half annuli) than is the case in any other known Ameri- 

 can species. The male pore is a conspicuous transverse opening ele- 

 vated on a broad low papilla in the middle of XII a.?, and the female 

 a very minute opening between the annuli XIII hi lb 2. Considerable 

 variation, in the posterior direction, occurs in the position of the 

 male pore. In about five per cent of the cases it has been found at 

 the posterior part of its annulus, in the succeeding furrow (XII 

 a2/b$) or even within the annulus XII bj. No variations in the posi- 

 tion of the female opening have been observed. Nothing of im- 

 portance can be noted with regard to the nephridiopores, anus or 

 posterior sucker. 



Concerning the annulation reference may be made to figures 33 

 and 34 on Plate V and figure 43 on Plate VI. Both somites II and 

 III appear to be biannulate and at least the outermost pair of eyes of 

 the anterior group are well within the latter. Somite V is also biannu- 

 late, VI triannulate and VII quadriannulate. Beginning with VII annu- 

 lus b6 shows its larger size and by IX is fully subdivided. In most of 

 the complete quinquiannulate somites, of which there are seventeen 

 (VIII to XXIV), this large size of b6 and its subdivision is very clear- 

 ly manifested. Toward the caudal end XXV is quadriannulate, XXVI 

 triannulate and XXVII two or three small rings behind the anus. 



Owing to maceration the characters of the testes cannot be satis- 

 factorily determined but apparently they are even smaller and more 

 numerous than usual in the family. The specialized anterior portion 

 of the vasa deferentia extends through, a smaller number of somites 

 than usual, the sperm sac reaching from ganglion XVI only to XIV or 

 thereabout, within which region it is of large size and much folded. 

 The pre-atrial loop of the ejaculatory canal reaches to ganglion XI and 

 just before entering the atrial cornua the duct is folded laterally sev- 

 eral times. The atrium itself has simply curved horns. Its median 

 part crowds the twelfth ganglion somewhat caudad out of its usual 

 position. 



