496 F. W. GAMBLE. 



Sub-order 3.— POLYCLADIDA. 



A. ACOTYLEA. 



Family PLANOCERIDiE. 



^ Mouth and pharynx subcentral. Main-gut rarely 

 extends in front of or behind the pharyngeal 

 sheath. Dorsal tentacles present. Eyes occur 

 (1) on or round the bases of the tentacles; (2) 

 as a double cephalic group; (8) on the body margin. 

 Development usually direct. 



Genus 27. — Planocera, de Blainville,^ 1826. 

 Body broad, leaf-like. Tentacles tapering, contract- 

 ing into temporary pits. Brain and tentacles lie 

 at the beginning of the second fourth of the body. 

 Marginal eyes absent. Pharynx at rest lies com- 

 pletely folded in its sheath. Two genital aper- 

 tures some distance from the hinder end. 



60. Planocera folium (Grube). 



1840. Stylochus folium, Grube (14). 



1844. Planoceea folium, Oersted (16). 

 1856. „ „ Johnstou (38). 



1884. „ „ Lang (54). 



Length 1*4 mm. Body extremely contractile, so that a 

 definite shape cannot be stated. The ground-colour is pale 

 yellow; the main-gut and its branches are brown, ending in 

 marginal black spots. Small white spots (due to the under- 

 lying ovaries) are dotted over the dorsal surface. On this 

 surface, nearly one fourth the length of the body from the an- 

 terior end, are the cylindrical tentacles, which are during 

 life capable of being suddenly extended and as quickly re- 

 tracted into pits. Round the bases of these tentacles are 



^ The definitions of families and genera of Pol^clads are taken from 

 Lang (54). 



2 de Blainville, ' Dictionnaire des Sciences naturelles,' art. "Planaire," 

 t. xli, 1826. 



