HISTOLOGY OP THE LAND-PLANARIANS OE CEYLON. 
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Rhyjychodemus r N. America. Leidy, Proc. Acad. Phil. 1851, pp. 241, 289 ; 
sylvaticus < 1858, p. 172. Said by Schmarda (Neue wirbellose 
( Thiere, 1859) to be very like terrestris. 
bistriatus ) Samoan Islands (Navigator Islands, Schiffer-Inseln). 
qiiadnstriatus . . . ) Grube. 
JSfietneri Ceylon. Humbert, Mem. Soc. Phys. Geneve, 1861, p. 306. 
And there may now be added 
tannagi . . . . . 
bilineatws ( Geodesmus ) 
Thwaitesii . . . 
Brazil. Ferussac, Ann. Gen. Sci. Phys. vol. viii. 1821, 
pp. 90-92. 
Giessen 1 ? Mecznikow, Bull. Acad. St. Petersb. 1865, 
vol. ix. p. 433. 
Ceylon. Mihi, 1872. 
In the absence of any accurate description of the anatomy of most of the animals 
included under this genus Bhynchodemus, the genus cannot yet be said to be very 
satisfactory. Observations on the anatomy of B. terrestris and B. sylvaticus are very 
much wanted. It is uncertain whether Mecznikow’ s Geodesmus , which, as Grube 
(Jahresbericht, loc. cit. p. 64) remarks, was probably not European, but introduced 
with foreign plants, should be considered a Bhynchodemus on account of its elongated 
body and single pair of eyes. At all events, as far as B. Thwaitesii and therefore B. 
Nietneri (which is evidently closely allied) are concerned, Diesing’s wide separation of 
the genera Bhynchodemus and Bipalium is unfortunate. The two genera are evidently 
closely allied in the presence in both of an ambulacral line, the absence of ramifications 
on the inner side of the posterior prolongation of the digestive tract, and in the arrange- 
ment of the muscular structures and viscera, as also in general facies, colouring, and 
habit. Stimpson (loc. cit. 1) is quite right in placing together the genera Geoplana , 
Bipalium, and Bhynchodemus ; but in his description of the subfamily the statement 
concerning the mouth will not apply to that of Bhynchodemus, and the discovery of eyes 
all down the body of Bipalium necessitates a further change in the definitions given both 
by Diesing and Stimpson. 
Altering slightly from Stimpson (loc. cit. 1, p. 24), the definition of the subfamily 
Geoplanidae will stand thus : — 
Geoplanid^e. — Corpus elongatum depressum vel depressiuseulum subtus pede sat 
distincto ; caput continuum vel discretum. Ocelli duo vel plurimi in capite solum aut 
etiam passim in corpore dispositi. Os postmediale. CEsophagus protractilis campa- 
nulatus margine ssepius sinuoso aut doliiformis. Apertura genitalis pone os. 
Under this subfamily there stand the three genera Geoplana, Bipalium, and Bhyncho- 
demus. The genus Bipalium was formed by Stimpson (loc. cit.) to include four species 
of remarkable Land-Planarians which he obtained on the U. S. A. Expedition under 
Captain Rodgers. The genus is an extremely well-marked one, being distinguished by 
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