Subfamily LIGULINAE. 



Diagnosis: Body without distinct external seg-menlation; lieatl 

 without suckers, or two slit-like suckers may develop; genital 

 pores ventral. Type genus Digula Bloch, ]782. 



Genus LIGULA Bloch. 1782. 



Diagnosis: Body not segmented externally, but the genital 

 organs are repeated and the three genital pores (Penis, vulva, 

 and uterine pore) of each set open ventrally; head without 

 distinct suckers, or 2 longitudinal slit-like suckers may de- 

 velo:i. 



Dife hist0'O':The larval form Hves in the alidominal cavity 

 of fish (particularly Cyprinidae). thr- adult in the intes.tine of 

 various piscivorous birds. 



This genus does not iiorinally occur in domesticated 

 birds, but Duchainp (187(J, quoted in Ducliamp, 1877) 

 infected ducks and pigeons (1877) widi the hival form 

 taken from the tencli (Tinea vulgaris); he also (1878A) 

 raised the adult in the peritoneal cavity O'f a dog. 

 Donnadieu (1877) fed young ligules to ducks, and after 

 twenty to thirty hours found adult ligules with eggs 

 iir these birds in some of his experiments, although in 

 other infections of ducks his I'esulls \v(M'e negative. 

 l{i(-hm (18S2) also succeeded in itifcrliiig dncks willi 

 ligules. 



From a piscicultural standpoint the immature stage of this 

 parasite is of considerable importance, for it occasionally gives 

 rise to serious epizootics among fish (for historical review, 

 of. Donnadieu, 1877). 



A la'Pge number of species have been insufflcien'tly described 

 by various authors. Donnadieu unites them all with Schisto- 

 cephalus under the name Diibothrium ligula; other authors, 

 however, are inclined to recognize two species, i. e., Ligula 

 uniserialis Rud.. 1810 (Syn. 1S39. L. monogramma Creplin). and 

 Ligula alternans Rud.. ISIO (Syn. 1S39. L. digramma Creplin). 

 The term L. simplicissima Rud.. 1S02. is generally applied to 

 the sexual form in fish. 



uniserial !>. uni.serialis. 



and allernating L. alternans. 



