CLASS. III. 
SEA-NETTLES (ACALEPH2)'. 
By Sea-nettles are understood radiate animals of a gelatinous, 
transparent substance, which swim freely, and of which the organisa- 
tion in parts that are frequently repeated usually indicates the number 
four or its double. They have no intestinal canal, but ordinarily a 
blind stomach from which numerous tubes, mostly divided into 
branches, run like rays to the circumference of the body (aquiferous 
vessels, respiratory organs?). In some the sexes are separate: 
others appear to be bi-sexual. Traces of a nervous system are 
present at least in some; yet organs of sense, except appendages 
which serve for feeling, are absent in many, whilst some have in 
addition parts which by certain writers are considered to be organs 
of hearing, by others organs of sight. 
Of the name Sea-nettles, Acalephe, Urtice marine, we have 
treated above. With LAMARCK they form an order of the class of 
radiate animals (Radiaires), under which this writer also groups 
1 On this class may be compared especially : 
F, Esouscwoirz, System der Acalephen, Mit 16 Kupfertafeln. Berlin, 1829, 4to. 
C. G. EaRENBERG, Die Acalephen des rothen Meeres und der Organismus der 
Medusen der Ostsee. Mit 8 colorirte Kupfertafeln. (Reprinted from the Phystkal. 
Abhandl. der Kinigl. Akad. der Wissenchaften zu Berlin aus dem Jahre 1835). 
Histoire naturelle des Zoophytes. Acaléphes par R. P. Lesson, av. pl. Paris, 
1843, 8vo. 
J. G. Wii, Hore Tergestine, oder Beschreibung und Anatomie der im Herbste 1843 
bet Triest beobachteten Akalephen. Mit 2 Tafeln, Leipzig, 1844. 
Epw. Forses, A Monograph of the British Naked-eyed Meduse, with figures of all 
the species. London, printed for the Ray Society, 1848, fol. 
_Huxiey, On the affinities of the Meduse. Phil. Transact. London, 1849, Pt. 11. 
p- 413 &e. 
On the Stphonophore : 
A. Korniiker, Die Schwimmpolypen, oder Siphonophoren von Messina. Mit 12 
Tafeln, Leipzig, 1853, fol. 
R. Levoxart, Die Siphonophoren, eine Zoologische Untersuchung, Giessen, 1853, 4to. 
R. Levucxart, Zur niihern Kenntniss der Siphonophoren von Nizza, Mit 3 Kupfertaf. 
Berlin, 1854, 8vo. 
C. Voer, Sur les Siphonophores de la Mér de Nice. Gendve, 1854. 
