FURTHER REPORT ON PARASITES. 53 



Tetragonocephalum, 11. gen. 



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

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

 a papilla. 



This genus would he a meinher of the family Lecanicephalidae, and would probably 

 come not very far from the genus Lecanicephalutn, Lint., in Braun's classification 

 given in Bronx's " Thierreich." 



The species above described may he forniallv 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 

 curling-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 CBtiobatidis, n. sp. Minute head not much more than visible 

 to the naked eye; length of body and head 1"5 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 Batistes sp. and the other 

 from either a species of Carcharias 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 tig. 11 on our Plate. 



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



This Trematode comes very near D. pattens,^ but differs from it in having certain 

 peculiarities which seem of specific rank. D. pattens was found in Chrysophrys 

 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 " liasking-shark." The " basking-shark " of 

 the Indian Ocean, according to the books, is the rather rare Rhinodon typicus, but Professor Hekdman s 

 llection is that the term was applied by the sea-going men to a Carcharias. A drawing of one of these 

 sharks caught on the pearl banks has, however, been identified by Mr. BOULENGEK as Stegostoma tigrinum. 



t RuDOLPHI, ' Entozoorum Synopsis,' 1819, pp. Ill and 410; Dujakdix, 'Hist. Nat. d. Helminthes,' 

 pp. 457 and 458; Diesim;, ' Syst. Helm.,' vol. 1, p. 348; StossicH, ' Saggio di una Fauna Elmint. di 

 Trieste,' p. 47 ; ' Ll.vioN, ' Proc. Nat. .Museum,' vol. 20, pp. ul'ti and 527, plate xlvii., figs. 8 and 9. 



