HISTOLOGY OF THE LAND-PLANARIANS OF CEYLON. 
Ill 
dissection. B. Proserpina in the young condition is marked exactly like the adults of 
the same species, but in this case the adults are conspicuously banded. 
The following are the characteristics of a new species of Bhynchodemus. In ascribing 
the speties to the genus Bhynchodemus I have followed M. Humbert, this animal being 
evidently of the same genus as his B. Nietneri. 
Bhynchodemus Thwaitesii, sp. nov., Plate X. fig. 4. The dorsal surface of the animal 
may be considered divisible into three bands, a median and two lateral, of about equal 
width : the median band light brownish yellow with a black line down its centre ; the 
two lateral bands violet-grey, very dark at the edges which bound the median band, but 
shading off into a light tint at their outer margin. The animal is thus five-striped. 
Ventral surface marked by a median white band, the ambulacral line bordered by 
darkish violet-grey. 
Dimensions of an average specimen after contraction in spirit : — 
millims. 
From tip of tail to generative orifice 10 
From generative orifice to mouth 12 
From mouth to tip of anterior extremity 22 
Entire length ... 44 
Habitat. The Royal Botanic Gardens, Peradeniya, Ceylon, occurring, together with 
three species of Bipalium, amongst fallen leaves &c. in plantations, especially abundant 
in Banana and Manilla-hemp plantations. The species I have named after my friend 
Mr. G. H. K. Tiiwaites, F.R.S., the distinguished Curator of the Peradeniya Gardens. 
On the Habits of Land-Planarians. 
Land-Planarians are probably all of them nocturnal in habit. Darwin (loc. cit. p. 249) 
remarks on the avoidance of light by Geoplana, and Dr. Leidy (loc. cit. 2, p. 172) observed 
Bhynchodemus sylvaticus to be a nocturnal animal crawling about on fences at night. 
Geoplana subterranea ( Geobia, Diesing), according to F. Muller, lives underground in 
the holes of Lumbricus corethrurus (Halle Abh. loc. cit. pp. 26, 27). The Ceylon Land- 
Planarians appear to avoid light in the same manner as the Geoplance ; they are to be 
found in dark places, such as under large fallen leaves, and in confinement they coil 
themselves up away from the light. 
This avoidance of light appears to be common to nearly all Planarians, and not con- 
fined to terrestrial forms. Max Schultze (loc. cit. 1, p. 17) refers to the fact that 
aquatic Planarians always choose the darkest side of any vessel in which they may 
be placed to rest upon ; and I have myself observed this fact in the case of Planaria 
torva and Hendrocoelum lacteum. Green chlorophyl-containing Planarians, such as Meso- 
stomum viridatum, form an exception to the general rule, since, as Max Schultze informs 
us (loc. cit. 1, p. 17), they always place themselves on the light side of a vessel: they 
nevertheless die when exposed to direct sunlight. It may have been due to the fact 
that I did not give them sufficient shade that all my attempts to keep the Ceylon Land- 
