THE LEECHES (HU^UDINEA) 



657 



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

 usually green with six or four brown stripes, sometimes 

 broken. European medicinal leech; introduced. 



lliriidu medUinalis Linnaeus 17 58. 



Fig. 1004. Htrudo medicinalts. External morphology from the dorsum. The numerals on the rishl 

 indicate the annuli, those on the left the somites, the index lines running to the ncuml annul!- 

 1st P. and 17th 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 scries; no penis; 



genital orifices separated by three or four rings, surrounded 

 by systems of gland pores. . Philobdella W-rriW iS-j 4. . 45 



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

 yellow stripes and a few brown spots. 



Philobdella gracUe Moore igoi. 



Philohdclla takes the place of Macro- 

 bdella in the Gulf States and has 

 singular habits. It is the native 

 "blood-sucker " of that ri-gion. 



Fig. 1005. Philobdflla gracile. A , external 

 genital orifices { $ , 9 ) wi'h their re- 

 spective svstems of pland (K)rcs icj;p J 

 and cppy); np, ncphridit>pt>rrs; tbrn. 

 vl, vm, submargmal, lateral, and mnlian 

 sensillae. X .^}. (After M.iorc.) /». 

 outlineof a jaw with te«lh. X .?S- <.\ftcr 

 Moore.) 



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



faint stripes of reddish brown separated b\- a narrow line of 

 blackish on each side of dorsum. 



Philohdelhi jloridana X'errill 1S74. 



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 live rings; no copulatory glands. 



IJiumopis Savigny 1S20 . . 48 



48 (51) Jaws and teeth present. 



49 



