44 
THE POLYPI. 
$$ 85, 86. 
it a cornea, a crystalline lensand a red pigment layer surrounding the 
whole. 
Furthermore, there are upon the border of the disc of the campanulate 
Campanularia, colorless corpuscles, containing a calcareous nucleus, which 
is transparent as a crystal and soluble in acid. : 
These organs should probably be regarded as the most simple form of 
the auditory organs, for they have only a simple vestibule with its single 
otolite.® 
\ 
CHAPTER V. 
DIGESTIVE APPARATUS. 
§ 35. 
The digestive apparatus of Polyps is formed after two different types. 
With the Anthozoa it consists of a mouth and a simple stomachal sac with- 
out an anus. 
But with the Bryozoa, there is a mouth and anus, and a 
digestive canal which may be divided into the sections of msophagus, 
stomach, small intestine and rectum. 
§ 36. 
The mouth of Polyps is usually surrounded by a circle of long, very 
contractile tentacles or arms. 
These tentacles are tubular, and connect with 
the cavity of the body.” They are simple,” or peunate,® and may be dis- 
posed around the mouth in a single or a multiple® circle ; they are also 
frequently covered with cilia.© 
Thus, the cylindrical tentacles of Actinia are entirely covered by ciliated 
epithelium. 
3 Quatrefages, Ann. d. Sc. Nat. XVIII. 1842, 
p 280, pl. VILL. fig. 1, d, d, and fig. 6. 
4 See Krohn (Miller’s Arch. 1843, p. 176) and 
Kolliker (Froriep’s neue Notizen, 1843, No. 534, p. 
81). Van Beneden has perceived in the campa- 
bulate and free individuals of Campanudaria ge- 
datinosa and geniculata, not only eight marginal 
bodies, each containing a calcareous nucleus, but 
also four nervous ganglia about the base of the 
stomach (Mém. sur Jes Campanulaires de la céte 
@stende, 1843, p. 24-27, pl. II. IIL). I am yet 
undetermined upon the question whether, as Van 
Beneden thinks, these bodies have sometimes the 
function of organs of vision, and sometimes that 
of organs of hearing. I am also in doubt as to the 
opinion of Huschke (Lehre von den Eingeweiden 
uud Sinnesorganen, 1844, p. 880), who regards as 
otolites the calcareous bodies which have been ob- 
served in the peduncle of Veretillum cynomo- 
rium. Nordmann (Versuch. einer Monogr. des 
‘Tergipes, p. 88) has described as auditory organs 
With the Bryozoa, on the contrary, the slightly-flattened ten- 
does not open outwards at the extremity of these 
organs. I doubt, in fact, if the Actinina are an ex- 
ception to this. It therefore appears singular that 
Rymer Jones (A General Outline of the Animal 
King. p. 41, fig. 13), and Lesson (Duperrey, Voy- 
age autour du Monde. Zoophytes, p. 82, No. 1, fig. 
1), expressly mention and distinctly figure these 
openings ; the first with an Actinia, the second 
with an Eumenides. According to Van Beneden 
(loc. cit. p. 15) the tentacles of Campanularia 
are withcut these cavities. But this is contradict- 
ed by Lovén (Wiegmann’s Arch. 1837, Bd. 1, p. 
252). In Hydra the cavities open distinctly into 
the stomach, asis probably the case with many other 
Hydrina. Frey and Leuckart likewise doubt the 
constant presence of an orifice at the apex of the 
tentacles of the’ Actiniae.* 
2 Actinia, Hydra, Flustra and Campanularia. 
3 Veretillum, Lobularia, Isis, Gorgonia, and 
Zoanthus. 
4 Hydra, Flustra, Zoanthus and Veretillum. 
the marginal bodies of the free-swi Campa 
anulariae. 
1 This cavity which is in the arms of most Polyps 
*[§ 86, note 1.) Subsequent researches have 
shown that the cavity of the tentacles does open 
externally thraugh a small papilla. See Dana, 
Actinia and Caryophyllia. 
6 Veretillum, Flustra, Eschara, Cristatella 
and Tubulipora. 
Structure and Classification of Zoophytes. Phil. 
1846, p. 82. — Ep. 
