5Sa 



Subfamily LIGULINAE. 



Diagnosis : Body without distinct external segmentation; head 

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

 pores ventral. Type genus Ligula Bloch, 1782. 



Genus I-,TGULA Bloch. 1782. 



Diagnosis: Body noi segmtnied exieinally, but the genital 

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

 and uterine pore) of each set open \ientrally; head without 

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

 velop. 



Liife histo'i-y :The larval foiin lives in the abdominal cavity 

 of fish (particularly Cyprinidae), the adult in the intestine of 

 \arious piscivorous birds. 



This genus does not normally occur in domesticated 

 birds, but Duchamp (1870, quoted in Duchamp, 1877) 

 infected ducks and pigeons (1877) with the laval form 

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

 laised the adult in the peritoneal cavity of a dog. 

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

 twenty to thirty hours found adult ligules with eggs 

 in these birds in some of his experiments, although in 

 other infections of ducks his results were negative. 

 I\iehm (1882) also succeeded in infecting ducks with 

 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, 

 cf. Donnadieu, 1877). 



A large number of species have been insufficien'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., 1810 (Syn. 1839. L. digramma Creplin). 

 The term L. simplicissima Rud.. 1802. is generally applied to 

 the sexual form in fish, 



J Oenital ni-eans simple, uniserial L. uni.serialis. 



i Genital organs double and alternating L. alternans. 



