HABITS OF TRICLADIDA 37 



and in one or two species of liltyncliodcnius. 1 Some Land 

 Planauans (a species of Rhynchodcmus from Ceylon, and a 

 Dolichoplana from the Philippines) wriggle out of a box or the 

 hand with great speed (Moseley). 



The skin of Triclads is full of minute rods or rhabdites, 

 which are shot out in great numbers when the animal is irritated, 

 and doubtless serve an offensive purpose. The Terricola possess 

 two kinds of these: (1) needle-like rods; and (2) in tiipalium 

 keioensc, flagellated structures, bent into a V-form and with a 

 slender thread attached to one end (Shipley). In Geoplana 

 cocrulea these bent rods furnish the blue colour of the ventral 

 surface. The rhabdites arise in all Triclads in cells below the 

 basement-membrane, which they are said to traverse in order to 

 reach the epidermis, thus differing in origin, and also in struc- 

 ture, from the rods of Polyclads. 



Food. Triclads are largely if not wholly carnivorous animals, 

 feeding upon Annelids, Crustacea, Insects, Insect-larvae, and Mol- 

 luscs. The mouth is usually mid-ventral or behind the middle 

 of the body, but in the anomalous Leimacopsis terricola Schm. 

 from the Andes 2 and in Dolichoplana it is near the anterior end. 

 The pharynx (Figs. 17, 18, pli) is cylindrical or bell-shaped, 

 exceedingly dilatable and abundantly supplied with glands and 

 nervous tissue. It opens into the three main intestinal branches, 

 one of which runs in the median plane forwards, the others back- 

 wards right and left, enclosing a space in which the genital ducts 

 lie (Figs. 14, A, 17). The fresh- water Planarians prey upon 

 Oligochaeta, Hydrophilidae (aquatic beetles), and the commoner 

 pond-snails. Bipalium keivensc pursues earthworms, seizes the 

 upper surface of the anterior end by the glutinous secretion of its 

 ventral surface and then proceeds to envelop part or the whole 

 of the worm within its pharynx, which is stretched as a thin skin 

 over the body of its struggling prey (Lehnert). The tissues of 

 the latter pass into the intestine of the Planarian, and distend it 

 greatly. After such a meal, which lasts from one to five hours, 

 a JJipalium may remain for three months without seeking food. 

 Gcohia siibterranca, a white eyeless form from Brazil, pursues 

 earthworms (Lumlricus corcthrurus) in their burrows, and has 

 been seen by Fritz Miiller sucking the blood out of a young 



1 Dendy, 1'roc. Roy. Soc. J r ictorla, vol. iv. n.s. i. 1802. 

 2 Schmarcla, A'ruc wirbcUusc T/ricrc, Leipzig, 1859, I. i. p. 30. 



