THE LEECHES (HIRUDINEA) 



657 



42 (39) No copulatory glands; penis filamentous; colors variable, dorsum 

 usually green with six or four brown stripes, sometimes 

 broken. European medicinal leech; introduced. 



Hirudo medicinalis Linnaeus 1758. 



FIG. 1004. Hirudo medicinalis. External morphology from the dqrsum. The numerals on the right 

 indicate the annuli, those on the left the somites, the index lines running to the neural annuli; 

 ist P. and i7th P., first and last nephridiopores. Natural size. (After Whitman.) 



43 (38) Jaws variable, sometimes rudimentary or absent; teeth when 



present all or partly in double series; gastric ceca one large 

 posterior pair only. Chiefly predaceous 44 



44 (47) Jaws short and high; teeth small, only partly in two series; no penis; 



genital orifices separated by three or four rings, surrounded 

 by systems of gland pores. . Philobdella Verrill 1874. . 45 



45 (46) Denticles about 35; narrow median dorsal and broader marginal 

 yellow stripes and a few brown spots. 



Philobdella gracile Moore 1901. 



Phttobdella takes the place of Macro- 

 bdella in the Gulf States and has 

 singular habits. It is the native 

 "blood-sucker " of that region. 



FIG. 1005. Philobdella gracile. A, external 

 genital orifices ( $ , 9 ) with their re- 

 spective systems of gland pores (cgp $ 

 and cgp 9 ) ; np, nephridiopores; sbm, 

 vl, vm, submargmal, lateral, and median 

 sensillae. X 35- (After Moore.) B, 

 outline of a jaw with teeth. X35- (After 

 Moore.) 



46 (45) Denticles about 20; no median dorsal stripe and no spots; two 



faint stripes of reddish brown separated by a narrow line of 

 blackish on each side of dorsum. 



Philobdella floridana Verrill 1874. 



47 (44) Jaws rather small and retractile into pits or absent; teeth when 



present coarse and all in double series; penis filamentous; 



genital orifices separated by five rings; no copulatory glands. 



Haemopis Savigny 1820 . . 48 



48 (51) Jaws and teeth present 49 



