PL.^NARTA TEMIESTIIIS IN KNOLAND. 195 



Diesing iu the ' Sy sterna Helmintlium,' p. 20G, describes it as 

 follows : — 



" Corpus sublineare, antrorsum angustatum truncatum, re- 

 trorsum rotundatum, supra convexum cinereum, subtus plani- 

 usculum album. Ocellus singulus in areola pallida. Longit. 6-8" 

 latit. 2_^". 



" Fasciola terrestris, Miiller, Ver. terr. etjluv. p. 68. 



"Planaria tkrrestris, Gtnelin, Syst. Nat. .30.92; Duc/h, Ann. Set. 



Nat. xxi. 82 ; Oersted, Krbyer's Natur. Tids. iv. 552, and Ent. ein. 



sj/s. Einth. d. Plattw. 55 in nota. 

 " Habitaculum. In asscribus muscisquc humidis, qua tcrram spcclant, 



Septembri et Novembri in Dania (Miiller) ; prope Languedociam 



(Duffh)." 



It has also been observed in Germany by Fritz Miiller and 

 Moll. 



In the ' Melanges Biologiques tires du Bulletin de I'Acadcmie 

 Imp. d. Sciences de St. Petersbourg,' 5th ser. vol. v., Mecznikow 

 describes a second terrestrial Flanaria under the name of Geodes- 

 mus hilineatus, expressing, however, some doubt whether it is not 

 the same as the P. terrcstris. Whether it ought to constitute a 

 new genus may perhaps be questioned ; but there can, I think, be 

 no doubt that it is a perfectly distinct species. 



On the other hand our English species completely answers to 

 the descriptions given by continental writers, and appears to be- 

 long to the true genus Planaria. Mr. Houghton, to whom I 

 showed my specimens, and who has found some in Shropshire, 

 is quite of the same opinion. It is pretty common in Kent 

 througliout the year in damp earth and decaying vegetable mat- 

 ter ; and I have little doubt that it has hitherto escaped observa- 

 tion owing to its being mistaken for a small Slug. 



This close similarity was observed by Miiller, who thought that 

 it consequently formed a connecting link between lAmax and 

 Hirudo. It is hardly necessary to say that this is entirely a mis- 

 take. The resemblance is altogether superficial ; but I do not 

 Icnow any instance of more complete similarity of appearance 

 between two animals belonging to such different divisions of the 

 animal kingdom. 



