TRICLADIDA 35 



certain parts of Victoria, New South Wales, and New Zealand. 1 

 About forty species of Planarians have been discovered on the 

 Australian continent, thirty-five of which belong to the pre- 

 dominant genus Geoplana, distinguished by the presence of 

 numerous eyes along the border of the simple anterior extremity. 

 Of the remaining five, four belong to the genus Bhynchodemus, 

 with, lastly, the introduced Bipalium, kewense. The distribution 

 of any one species, however, is so limited that only three forms 

 are common to the two former colonies ; and although some of 

 the twenty known New Zealand Planarians (chiefly species of 

 Geoplana), are identical with Australian species, yet only one, or 

 possibly two, varieties of these species are Australian also. In 

 addition to their prevalence in Australasia, the Geoplanidae also 

 occur in South America, South Africa, Japan, and the East Indies. 

 The Bipaliidae are characteristic of the Oriental region, being 

 found in China, Borneo, Bengal, and Ceylon. The Rhyncliode- 

 midae are a cosmopolitan family, occurring in Europe, North and 

 South America, the Cape of Good Hope, Ceylon, the East Indies, 

 Australia (particularly Lord Howe Island), and Samoa. 2 



Habits and Structure of Triclads. The common Planaria 

 (Dendrocoelum) lactea, which usually progresses by ciliary action, 

 aided, it is said, by muscular contractions of the ventral surface, 

 performs, if alarmed, a series of rapid " looping " movements, by 

 affixing a sucker (Fig. 14, A, sc), placed on the under side of the 

 head, to the substratum, and pulling the posterior end close to 

 this. The sucker, discovered by Leydig, is even better developed 

 in P. punctata (Fig. 16, A), P. mrazekii, and P. cavatica, and is 

 an efficient adhering-organ which has probably been developed 

 from a similar but simpler structure found in a considerable 

 number of both fresh-water and marine Triclads (P. alpina, Fig. 

 16, E). Probably the sucker of the Land Planarian Cotyloplana 

 (D) is the same structure, but the two suckers of Dicotylus (B) 

 are at present unique. Plhnaria dioica, found by Claparede on 

 the coast of Normandy, 8 is covered with minute adhesive papillae, 



1 Trans. Roy. Soc. Victoria from 1889 onwards. Trans. New Zealand Institute, 

 1894-95. 



2 Moseley, Phil. Tr^ns. 1874, p. 105 ; Id. Quart. Journ. Micr. Sri. vol. xlvii. 

 1877, p. 273 ; Loman, Bijdrag tot d. Dierkunde, Aflev. 14, 1887, p. 71 ; Id. Zool. 

 Ergeb. ein. Reise in Nieder-Ost-Indien, Hft. 1, p. 131 ; Beddard, Zoogeography, 

 1895, p. 53. 



3 Beobachtungen ii. Anat. u. Entwickel. under Kiiste von Normandie, 1863, p. 18. 



