34 MALACOBDELLID/E. 



Nitschia elougata, Moq.-Tandon, Monogr. 394. 



Tristoma sturionis, E. Bkmchard in Ann. des Sc. nat. viii. 329 (1847)- 



Hah. The gills of the Sturgeon. Found on Jcipenser acutirostris, 

 Parn., taken on the coast of Scotland by Dr. Melville. 



5. UDONELLA. 



Udonella, Johnston in Loud. Mag. Nat. Hist. viii. 498. Dies. Syst. 

 Helm. i. 427. 

 Char. Body subcylindrical : head cuneate and truncate, with two 

 oblique marginal oblong bothria : mouth between the bothria, with 

 a short bell-shaped proboscis encircled at the orifice with a double 

 series of papillse : sucker terminal, sessile, urceolate : sexual aper- 

 tures ventral and forwards. 



1 . U. caligorum. 



Udonella caligorum, Johnston in Loud. Mag. Nat. Hist. viii. 497. 

 f. 45. W. Thompson in Ann. Sf Mag. Nat. Hist. xv. 320. Dies. 

 Syst. Helm. i. 427. Dalyell, Pow. Great, ii. 13, & i. pi. GG. f. 11. 



Hab. Parasitical on the Caligus of the Holibut. 



II. RHABDOCCELA. 

 Fam. III. MALACOBDELLID^. 



Bdellomorphes, E. Blanchard in Ami. des Sc. nat. xii. 275(1849). 

 Cnar. Body flattened, exannulose, smooth, with a circular saucer- 

 shaped sucker at the posterior extremity. Mouth anterior, marginal, 

 edentulous, minutely papillose : intestinal canal simple, with a vent 

 above the sucker. There is no heart, but the circulating system is 

 well developed and copiously ramified. The respiration is cutaneous. 

 The nervous system is bilateral. The sexes are separate ; and the 

 female is oviparous. 



6. MALACOBDELLA. 



Malacobdella, Blainville in Diet, des Sc. nat. xlvii. 270; ibid. hn. 



566; and in Cuv. Regn. Anim. iii. 217. Blanchard in Ann. des Sc. 



nat. iv. 373 (1845), and viii. 142 (1847). Diesing, Syst. Helm. i. 



445. 

 Xenistum, E. Blanchard in lib. cit. 142. 



Char. Body oval or oblong : sexual orifices towards the front : 

 mouth in a frontal emargination, villous internally : sucker attached 

 at the centre, unarmed, large. 



