i8 
THE ESSEX NATURALIST. 
to 25 days. Multiplication by transverse fission has not been 
noted although the species easily recovers from injury (p. 2). 
Distribution :— 
Britain. Very common, and occurs in almost every pond. 
France, Germany, Switzerland, Sweden, Russia. 
Polycelis cornuta Johnson. Fig. 7. 
Synonyms : Planaria cornuta Johns. 
Planaria viganensis Duges (?) 
Planaria Felina Dalyell. 
Description. Attains a length of 18 m.m. Readily recognized by 
the numerous eyes which pass across the frontal margin and along part of 
the body, and by the well-developed tentacles. General outline similar 
to that of PI. alpina, but readily distinguished by the character of the 
eyes. Colour, grey to black or greenish. Pharynx very long, sometimes 
measuring one-third the animal’s length. Mouth about three-quarters 
of the way down the body. Lobe-formula of intestine 13-15, 2 (4-6), 
13 - 15 - 
Habits. Occurs gregariously in cool streams. (See p. 10). 
The cocoons are spherical and are not attached to any object. 
Multiplication by transverse fission is very common. Dalyell 
(6) states that on the 10th of November, 1810, he detached a 
small fragment from the tail of each of two planarians of this 
species. Twelve days afterwards each fragment had produced 
a head ! 
Distribution :— 
Britain. Edinburgh (Dalyell) ; Seven Arches, Nr. Leeds ; 
Grassington, Yorks. (H.W.) 
France, Pyrenees, Germany, Italy, Switzerland, Sweden, 
Russia. 
BIBLIOGRAPHY. 
(1.) Baer, C. E. von. (1827), Beitrage zur Kentniss der niederen Tiere 
VI. Uber Planarien. Nova Acta Acad. Caes. Leop. Car. Naturae 
Curios, vol. xiii., 2, pp. 690-730. 
(2.) Benham, W B. (1901), Platyhelmia, Mesozoa,etc., in E. R. Lankester’s 
Treatise on Zoology, pt. IV. 
(3.) Bohmig, L. (1909), Tricladida in Brauer’s Susswasserfauna Deutsch - 
lands, Heft 19. 
(4.) Bresslau, E. (See Steinmann und Bresslau.) 
(5.) Chichkoff, G. D. (1892), Recherche s sur les Dendrocoeles d’eau 
douce. Archives de Biologie, XII , p. 435 + 
(6.) Dalyell, J. G. (1814), Observations on some interesting phenomena 
on animal physiology exhibited by several species of Planariae. 
(7.) Dalyell, J. G. (1851-1858), Powers of the Creator, vol. ii. 
