AQ THE POLYPI. $$ 31, 32. 
t 
With Eschara there are, moreover, two fasciculi in each cell, which move 
its operculum, and thus close the entrance of this cavity. 
§ 81. 
Locomotion is performed by the Polyps in various ways. 
With the Hydrae, by their long-stretching arms; with Actiniae, by the 
contractions of the disc of their foot ; ® while the Edwardsiae, having elon- 
gated bodies which are not attached by a foot, progress by vermiform 
movements.” With Cristatella mirabilis, the whole colony moves itself 
along by the foot-like basis, like the Actiniae.© 
Some Polyps, at a certain period of their development, move freely in 
the water by discoid contractions of their body, like the pulmograde 
Acalephae.® 
§ 32. 
A very remarkable peculiarity is the presence, in certain Bryozoa, of 
organs shaped like a bird’s head, and which swing to and fro at the base: 
of their cells. 
In some species, these organs have the form of lobster’s 
claws, being composed of both a fixed and a movable piece. 
This last is. 
corneous, and moved by a muscle which arises from a cavity in the first. 
It is not yet known by what means either this beak is opened, or the 
whole organ moves to and fro.® 
Equally unknown is the function of these singular organs, the move- 
ments of which persist after the death of the animal, and of which, there- 
fore, they are independent.” They are perhaps organs of defence or pre- 
hension, and analogous to the Pedicellarie of the Echinoderms. 
muscles of P7umatelia (Comp. rend. XII. 1841, p. 
724; Miiller’s Arch. 1842, p. ccx).* 
6 Milne Edwards, Aun. d. Se. Nat. loc. cit. p. 
94, pl. I. fig. 1, e. 
1 Berthold, loc. cit. p. 14. 
2 Quatrefages, Ann. d. Sc. Nat. XVII. p. 74; 
also Forbes, Ann. of Nat. Hist. VIII. 1842, p. 243. 
8 I have been able to confirm the observation of 
Dalyell (Froriep’s Notizen 1834, No. 920, p. 276) 
upon this motion in Cyistatella. Trembley, also, 
-has observed that the corallum of Plumatel/a 
cristata moyed half an inch in eight days (see 
his Mémoire pour servir a ’Hist. des Polypes d’eau 
douce, 1775, p. 298). 
4 See the observations of Steenstrup (Ueber d. 
Generationswechsel, 1842, p. 20) upon Coryne fri- 
tillaria ; also those of Van Beneden (Mém. sur les 
Campanulaires, 1843, p. 29, or Froriep’s neue Noti- 
zen, 1844, No. 663, p. 38) upon Campanularia ge- 
latinosa. 3 
i 
*[§ 30, note 5.] Allman (Report Brit. Assoc. 
1850, p. 314) has described a very complete mus- 
cular system in the fresh-water Bryozoa. Inthe 
species with bilateral lophophores, there are seven 
distinct sets : 1. Retractor muscles of the polypide; 
2. The rotatory muscles of the crown; 3. The 
tentacular muscles ; 4. The elevator muscle of the 
valve; 5. Superior parieto-vaginal muscles; 6. 
Inferior parieto-vaginal muscles ; 7. Vaginal sphinc- 
ter. The walls of the stomach also contain circular 
muscular fibres. 
1 These organs were first described by Ellis: 
(Essai sur l’Hist. Nat. des Corall. 1756, p. 51, pl. 
XX. fig. A). Nordmann (Observ. sur la Faune: 
Pontique, 1840, p. 679, pl. III. fig. 4) has described. 
and figured them with much accur: In Cel- 
laria avicularis, Bicellaria ciliata and Flustra 
avicularis, they are formed like lobster’s claws. 
In Retepora cellulosa they are pincer-like, and in 
Telegraphina they are articulated stings. See 
also Krohn in Froriep’s Notizen, 1844, No. 533, 
For the organs having the form of a bird’s head. 
end a lash, and which are present in certain Bry- 
ozoa, see also Van Beneden, Recherch. sur Vanat. 
&c., des Bryozoaires, in the Nouv. Mém. de Brux- 
elles, XVIII. 1845, p. 14, pl II. III., and Reid in 
the Ann. of Nat. Hist. XVI. 1845, p. 385, pl. XIL. 
a Voyage of the Beagle, 1844, pt. I. 
p. 252. 
With Paludicella, the muscular system is some+ 
what different ; there are here five sets, — the 1st. 
5th, 6th, and 7th of the preceding, and the parie- 
tal muscles. But with the 1st there is here only a 
single instead of a double fasciculus. — Ep. 
+ [§ 32, note 2] See Hincks (Ann. Nat. Hist. 
VIII. 1851, p. 353), who regards these avicularia 
as organs of defence, and has observed them seiz- 
ing and retaining foreign bodies. — Ep. 
