HISTOLOGY OF THE LAND-PLANARIANS OF CEYLON. 
113 
1861, p. 294). Bipalium , as is observed by this author, when moving carries its head 
slightly elevated, and moves it from side to side, evidently investigating with it any 
obstacles which occur in the line of movement. When the semilunar head is thus 
made use of, there are projected from its narrow anterior border tentacular-like eminences, 
which appear to be used as feelers. The tentacles are evidently not localized, but may 
be formed at any spot on the border of the head by contraction of surrounding tissue. 
M. Humbert searched for some corresponding permanent papillae or sense-organs on the 
border of the head without success ; but I have been more fortunate, and have found a 
peculiar narrow line of delicate papillae in this region, evidently connected with the 
sensory function of this part of the head, and which will be described in the sequel. 
See Plate XIII. figs. 16 & 17, and their accomanying descriptions. 
The following is a list of the works and memoirs concerning Planarians and allied 
forms which have been consulted, and to which reference is made in the present paper. 
Pallas Spicilegia Zoologica, Hft. 10. 1774. 
0. F. Muller 1. Yermium terrestrium et fluviatilium, seu Animalium Infusoriorum, Helminthi- 
corum, et Testaceorum, non marinorum, succincta historia. Hafnise et Lipsioe, 
2 vols. 4to, 1773-74. 
2. Zoologiae Danicse Prodromus, ii. p. 698. 1776. 
3. Zoologia Daniea, vol. iii. p. 49. 1789. 
J. R. Johnson Philosophical Transactions, 1822, pp. 437-446 ; 1825, pp. 247-253. 
C. E. yon Baer TTeher die Planarien. Nova Acta, tom. xiii. pt. 2 (1827), p. 690. 
Duels 1. Recherches sur l’organisation et les mceurs des Planaries. Ann. Sci. Nat. xv. 
(1828), p. 139. 
2. Apergu de quelques observations nouvelles sur les Planaires et plusieurs genres 
voisins. Art. 3. Planaires. Ann. Sci. Nat. xxi. (1830) pp. 81-90. 
Ehrenberg Turbellaria. Symbolse Physicse. 1830. 
Mertens Untersuchungen iiber den innern Bau verschiedener in der See lebender Plana- 
rien. Mem. Acad. St. Petersb. 6 C ser. tom. ii. (1833) pp. 3-19. 
Ehrenberg Lie Akalephen des rothen Meeres und der Organismus der Medusen der Ostsee. 
Abhandl. Berlin Akad. 1835, p. 181. 
Dr. Gray Zoological Miscellany, 1835, p. 5. 
F. Schulze De Planariarum vivendi ratione et structnra Dissert. Berol. 1836. 
Dr. Cantor On the Flora and Fauna of Chusan. Ann. & Mag. Nat. Hist. ix. (1842) p. 265. 
Charles Darwin Brief descriptions of several terrestrial Planarise and of some marine species, with 
an account of their habits. Ann. & Mag. Nat. Hist. xiv. (1844) p. 241. 
A. S. Oersted Entwurf einer systematischen Eintheilung Plattwiirmer. 1844. 
A. de Quatrefages Etudes sur les types inferieurs et de l’embranchement des Anneles. Memoire 
sur quelques Planaires marines. Ann. Sci. Nat. ser. 3, tom. iv. (1845) 
p. 129. 
Leonard Jenyns Observations in Natural History. London, 1846. 
Frey und Leuckart Lehrbuch der Anatomie wirbelloser Thiere. Leipzig: C. Yoss, 1847. 
E. Blanchard Recherches sur l’organisation des Yers. Ann. Sci. Nat. vi. (1847) pp. 106-116, 
viii. (1847) pp. 143-149. 
H. Frey und R. Leuckart . . Beitrage zur Kenntniss wirbelloser Thiere. Braunschweig, 1847. 
E. O. Schmidt Die Rhabdoccelen des siissen Wassers. 1848. 
MDCCCLXXIV. 
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