FRESH-WATER BIOLOGY 



12 (ll) 



13(4) 



14 (27) 



15 (16) 



16 (15) 



Relatively short, broad and flat; cutaneous papillae absent or in 

 I to 5 series, small or large, often double; deeply pigmented 

 in narrow longitudinal lines, or diffusely with metameric 



'° white spots on neural annuli; gastric ceca six pairs, simple. 



Glossiphonia fusca Castle 1900. 



This species is very variable, especially in the character of 

 the dorsal cutaneous papillae which may be scarcely evident 

 and limited to a median series on a few segments, or large and 

 conspicuous and arranged in five series extending for the en- 

 tire length, or in any intermediate condition. Those of the 

 median series are formed of a pair of papillae more or less 

 completely coalesced. Usually they are deeply pigmented 

 and contrast strongly with the clear white spots flanking 

 them. The eyes are unusually large and conspicuous. It 

 lives in ponds but also in colder waters than most species of 

 the genus, even in springs, and attaches itself to the larger 

 water snails and more rarely to leeches. The eggs, Hke 

 those of Glossiphonia complanata, are laid in a few large 

 gelatinous capsules borne on the venter of the parent leech 

 and breeding is continued to midsummer. Glossiphonia fusca 

 is much less active than Glossiphonia complanata and feeds 

 less frequently upon worms and larvae, preferring snails. 



Fig. 997. Glossiphonia fusca. General anatomy showing external 

 outline, segmentation and annulation, alimentary canal, re- 

 productive organs, etc. I-XXVII — somites; 2-70, annuli; pro, 

 proboscis; Po $ , male orifice; Po 9 , female orifice; ov, ovary; 

 oe, esophagus; iglv, stomach or crop; te, testes; ga and in, in- 

 testine; an, anus; dt. ej, ductus ejactulatorius. X 10. (Modified 

 from Castle.) 



Eyes three pairs n 



Genital pores separated by one annulus; eyes in three groups of 

 two, in a triangular figure; body transparent, with little 

 pigment; no papillae; gastric ceca six pairs, nearly or quite 

 unbranched. . . Glossiphonia heteroclita (Linnaeus) 1758. 



Genital pores separated by two annuli; eyes in two nearly parallel 

 rows; body rather thick and opaque, usually deeply pig- 

 mented, a pair of dorsal and ventral dark, narrow lines run- 

 ning for nearly entire length; gastric ceca seven pairs, 

 slightly branched. . Glossiphonia complanata (Linna-eus) ij $8. 



Epididymis more or less complexly and compactly folded in vi- 

 cinity of atrium ; salivary glands usually compact. . . 14 



One pair of anterior compound eyes; gastric ceca seven pairs, 

 usually much branched; saUvary glands compact; size mod- 

 erate to large. Temporary parasites on water turtles, frogs 

 and fishes; most species also free-living. 



Placobdella R. Blanchard 1893 . 15 



Somites I-V distinctly widened to form a discoid "head." Somites 

 I and II biannulate; dorsum with three strong papillated 

 keels. On fishes and frogs. . Placobdella monHferaMooieigi 2. 



Somites I-V not especially widened 17 



