FURTHER REPORT ON PARASITES. 53 



Tetragonocephalum, n. gen. 



Head unarmed, consisting of an anterior knob-like portion arising from a cubical 

 base ; the four posterior corners of the cubical base have minute suckers, each with 

 a papilla. 



This genus would be a member of the family Lecanicephalidte, and would probably 

 come not very far from the genus Lecanicephalum, LINT., in BRAUN'S classification 

 given in BRONN'S " Thierreich." 



The species above described may be formally defined as follows : 



Tetragonocephalum trygonis, n. sp. Fragile, minute, head hardly visible to the 

 naked eye ; length of body 2-4 centimetres : in section the head is circular and the 

 proglottides almost so, their greater diameter being 0'03 millim. ; head consisting of a 

 curliug-stone-shaped anterior portion resting on a square cushion with suckers at 

 each corner from which a papilla protrudes ; neck short ; furrows between contiguous 

 segments very slight and in some places invisible ; reproductive pores lateral and 

 irregularly alternate ; genital recess large, and the remains of this constrict the 

 ripe uterus into a dumb-bell-shaped structure. 



Tetragonocephalum cetiobatidis. n. sp. Minute head not much more than visible 

 to the naked eye; length of body and head T5 centims. ; head consists of an 

 elongated rostellum, unarmed, which projects freely from an almost cubical base, this 

 base is as long or longer than it is broad ; at its anterior angles it bears four small 

 suckers ; there seems to be no, or at most a very short, neck ; the proglottides 

 overlap. 



II. TREMATODA. 



In the following account of two Trematodes, one from Balistes sp. and the other 

 from either a species of Carcltanan or Rhinodon typicus, the " basking shark"* of 

 tropical waters, we are much indebted to Mr. NORMAN MACLAREN both for notes on 

 the structure of the animals and for the drawing of fig. 1 1 on our Plate. 



Distoma palleniscum, n. sp. Plate, fig. 11. 



This Trematode comes very near D. pallens, t but differs from it in having certain 

 peculiarities which seem of specific rank. D. pallens was found in Cbrytophrtfg 

 aurata, Cuv., by the authors mentioned in the footnote, and by LINTON in Alutera 



* There is some doubt as to the host represented by the " basking-shark." The " basking-shark " uf 

 the Indian Ocean, according to the books, is the rather rare lihiiuxhii ////'"*, but Professor HKKDMAN s 

 recollection is that the term was applied by the sea-going men to a Cairliin-ix. A drawing of one of these 

 sharks caught on the pearl banks has, however, been identified by Mr. BoULENQKB as Sfegostoma ti<jruniin. 



t ItUDOLi'in, ' Entozoonim Synopsis,' 1819, pp. Ill and 410; DvJAKDix, 'Hist. Nat. d. Helminthes,' 

 pp. 457 and 458; DIESING, ' Syst. Helm.,' vol. 1, p. 348; STOSSICH, ' Saggio di uiia Fauna Elmint. di 

 Trieste,' p. 47 ; ' LINTON, ' Proc. Nat. Museum,' vol. 20, pp. 526 and 527, plate xlvii., tigs. 8 and 9. 



