58 FLATWORMS AND MESOZOA, ETC. 



Turbellaria are carnivorous, overpowering their prey by pecu- 

 liar cutaneous, offensive weapons, and sucking oul the contents of 

 their victims by the " pharynx." Land Planarians feed on earth- 

 worms, molluscs, and woodlice ; fresh-water Planarians on Oligo- 

 chaet worms, water-snails, and water-beetles ; marine forms devour 

 Polychaet worms and molluscs, 



"An account of the Polyclad Turbellaria may be fitly pre- 

 faced by a description of a very common representative, Lepto- 

 plana tremellaris^ so called on account of the thin, flat body which 

 executes, when disturbed, quivering or tremulous swimming move- 

 ments. . . . Like all Polyclads, Leptoplana is marine. It is 

 probably found on all European shores, northwards to Greenland 

 and southwards to the Red Sea ; while vertically it ranges from 



the littoral zone down to fifty fathoms At low water, 



Leptoplana may be found buried in mud or on the under surface 

 of stones, in pools where darkness and dampness may be ensured 

 till the return of the tide." 



The anatomy of this worm is given at great length ; we shall 

 make only sufficient extracts from the author's voluminous des- 

 cription to enable Plate VIL, which has been kindly placed at 

 our disposal by the publishers, to be understood. 



Leptoplana may be divided into corresponding halves only by 

 a median, vertical, longitudinal plane. The body and all the 

 systems of organs are strictly bilaterally symmetrical. Excepting 

 the cavities of the organs themselves, the body is solid. . 

 The epidermis is composed of a single layer of ciliated cells, con- 

 taining small, highly refractive, pointed rods, or " rhabdites," and 

 gives rise to deeply-placed mucous cells, which are glandular, and 

 pour out on the surface of the body a fluid in which the cilia 

 vibrate. 



The general arrangement of the Digestive system may be seen 

 in Plate VIL, and may be compared, especially when the pharynx 

 is protruded, with the gastral system of a Medusa. The " mouth " 

 (there is no anus) is placed almost in the centre of the ventral 

 surface. It leads into a chamber (the peripharyngeal space), 

 divided into an upper and lower division by the insertion of a 

 muscular collar-fold (the pharynx,//^.), which may be protruded, 

 its free lips advancing through the mouth, and is then capable of 



