244 Mr. Darwin on several Planariaa, 



within any of the terrestrial species. The texture of the body, 

 its prompt dissolution into fluid after death, its power of healing 

 wounds, its irritability and contractile powers, appear to be ex- 

 actly similar in the terrestrial and in the aquatic species, as de- 

 scribed by Duges. I will not here repeat the description which 

 I have given in my Journal (p. 31) of the bisection of the P. Tas- 

 maniana, and the production of two perfect individuals (with the 

 exception of the external orifice for the mouth-sucker) in the 

 course of twenty-five days. I will only add, that an individual 

 being divided into many fragments, each crawled in the proper 

 direction, as if furnished with its proper anterior extremity. 



I found altogether twelve terrestrial species; two in the 

 forests of Brazil ; three on the grassy, open country northward 

 of the Rio Plata ; one on the arid hills near Valparaiso in Chile, 

 and three in the damp wooded country southward of central 

 Chile : the most southern locality was in lat. 46° 30' S. I found 

 also one species in New Zealand (which I lost), another in Van 

 Diemen's Land, and a third at the Mauritius ; the latter I had 

 not time to examine. Hence it appears that the terrestrial sec- 

 tion of this genus is widely diffused ; but as far as is at present 

 known, only in the southern hemisphere. The existence of ter- 

 restrial Planaria is analogous to that of terrestrial leeches in the 

 forests of southern Chile and of Ceylon. 



1. Planaria vaginuloides. 



Alimentary orifice situated at two-thirds of the entire length of 

 the body from the anterior extremity ; width of orifice -^ th of an 

 inch : at the distance of ^jths of an inch posteriorly, lies the genital 

 orifice, very plainly marked. Ocelli numerous, placed at regular in- 

 tervals on the anterior extremity ; irregularly, round the edges of the 

 foot. Anterior part of the body elongated, with the extremity much 

 pointed and grooved on the under side : tail bluntly pointed ; body 

 convex, flattened on the top. Sides and foot coloured dirty " orpi- 

 ment orange *" ; above, with two stripes on each side of pale " prim- 

 rose-yellow," edged externally with black ; on centre of the back a 

 stripe of glossy black ; these stripes become narrow towards both ex- 

 tremities. Length when fully extended 2 T 3 u ths of an inch ; breadth 

 in broadest part y^tus of an inch. 



Hob. Under the bark of a decayed tree in the forest : Rio de Ja- 

 neiro (June). 



2. Planaria elegans. 



Position of the orifices as in P. vaginuloides. Anterior part of the 

 body little elongated. Ocelli absent on the anterior extremity, and 

 only a few round the margin of the foot. Colours beautiful ; back 

 snow-white, with two approximate lines of reddish brown ; near the 



* The colours, when placed between inverted commas, signify that they 

 are given by comparison with Patrick Syme's Nomenclature. 



