666 THE ANIMAL KINGDOM. 



5. Pseudophyllidea : head provided with two sucking grooves. Proglottides 

 not always well defined. A uterine aperture. Embryo, so far as known, ciliated, 

 and egg-shell provided with an operculum. Bothriocephalus, Triaenophorus ( = Tri- 

 cuspidaria), Solenophorus, Schistocephalus, Ligula. The genus Duthiersia appears 

 to belong here. 



6. Caryophyllaeidae : no proglottides. Head end expanded and mobile. 

 ? development. Caryophyllaeus, from the intestines of Cyprinoid fishes. 



7. Amphilinidae : supra, p. 665. 



The position of the genus Leuckartia of Moniez, and P. J. van Beneden's 

 Abothrium, is uncertain. 



For lit. see pp. 228, 238. 



Duthiersia (from Varanus), Perrier, A. Z. Expt. ii. 1873. Leuckartia (from 

 Salmon), Moniez, ' Les Cestodes,' Travaux Zool. Inst. Lille, iii. pt. 2. Abothrium 

 (from Cod), Id. ibid. Polypocephalus (from Rhinobatis\ Braun, Arb. Zool. Zoot. 

 Inst. Wurzburg, iv. 1877-78. Echinoccoid from the Earthworm, Leuckart, 'Para- 

 siten,' i. (ed. 2) p. 464. 



Origin of Cestodes, Schneider, in his Zool. Beitrage, i. 1885. 



Head of Tetrarhynchus, Pintner, Arb. Zool. Inst. Wien, iii. 1881. 



Nervous system of Tetrarhynchus, Lang, Mitth. Zool. Stat. Naples, ii. 1881 ; of 

 Ligula, Schistocephalus, and Bothriocephalus, Niemiec, Arb. Zool. Inst. Wien, vii. 

 (i), 1886. 



Genital organs of T. litter ata, Zschokke, Z. A. viii. 1885 ; of T. elliptica and 

 Triaenophorus, Steudener, Abhandl. Natf. Ges. zu Halle, xiii. 1877. 



Direct development of T. serrata (!), Me'gnin, A. N. H. (5) xi. 1883. Cysticercus 

 racemosus (a form of C. cellulosae], Zenker, Beitrage zur Anat. &c. als Festgabe zu 

 Jacob Henle, Bonn, 1882. Cystic forms of Taeniae, Villot, A. Sc. N. (6), xv. 1883. 

 Scolex of Tetrarhynchus, Hoek, Niederland. Archiv f. Zoologie, v. 1879. Embryonic 

 development of Bothriocephalidae (= Pseudophyllidea] Schauinsland, J. Z. xix. 1885. 

 Host of Bothriocephalus latus, Braun, Zur Entwickelungsgeschichte des breiten 

 Bandwurmes, Studer, Wurzburg, 1883; cf. Z. A. iv., v., vi. Life history of Ligula, 

 Donnadieu, Journal de 1'Anat. et Physiol. xiii. 1877. 



CLASS TURBELLARIA. 



Unisegmental Vermes^ with a ciliated ectoderm in which are found 

 rhabdites, pseudo-rhabdites, or nematocysts ; with two cerebral ganglia con- 

 nected transversely, each of which is continued backwards into a long nerve, 

 with a mouth and muscular pharynx, but no anus ; with an excretory system 

 of tubes ending in flame-cells, and a coelome formed by spaces between the 

 parenchyma and viscera when it is present at all. Respiratory and circula- 



1 The marine Triclad, Gunda segmentata, is divided (but not externally) into 25 segments by 

 septa formed chiefly by the dorso-ventral muscles. There are 25 simple and paired lateral branches 

 to the intestine ; a pair of ovarie^ with 24 pairs of vitellaria, and 25 pairs of testes. The genital 

 organs correspond to the septa. The excretory canals open dorsally and probably by segmentally 

 arranged pores. A similar segmentation is indicated, but much less markedly, in other Tricladida. 



