702 CUABS KI. 
connexion to be detected, not at least, according to Minne Epwarps, 
in Polyclinum. 
Family II. Luce. Apertures of external covering opposite, 
terminal. Branchial sac girdled anteriorly by a membranous denti- 
culate ring, open posteriorly. Several animals aggregated to form 
a compound body swimming freely, cylindrico-conical, hollow 
internally. 
Pyrosoma PERON. 
This genus of compound A scidie was first discovered by PERon and 
his fellow-voyagers in the Atlantic ocean under the Tropics, when in 
a dark night numerous specimens of it appeared to form a broad 
band of light across the sea. From this phosphoric quality, the 
name (/%re-body) is derived. At first these compound animals were 
supposed to be a single animal, and the single individuals of which 
a Pyrosoma is compounded, to be little tubercles on the surface 
of the animal. See Prron Mém. sur le nouveau genre Pyrosoma, 
Ann. du Muséum, tv. pp. 437—446. For a more accurate know- 
ledge of this remarkable genus we are indebted almost exclusively 
to the investigations of Savieny. The compound body is a much- 
elongated cone, ordinarily six or seven inches in length, open at 
one end and at the other closed and bluntly rounded off. The 
little animals are placed perpendicularly to the axis of the cone, in 
circles more or less irregular, whilst the posterior openings of their 
body terminate in the cavity of the cone. The gem, according 
to the observations of Saviany, is already cloven into four animals 
even before they are born. Thisis the commencement of the cylin- 
der or cone, which may be imagined to be formed of a series of 
circles or girdles of small Ascidie behind each other of increasing 
size ; the thinner closed extremity of the compound body is thus 
the first formed. Consult Savieny 1. cit. pp. 58, 206. 
Sp. Pyrosoma atlanticum PERON, 1. 1. Pl. 72, Voyage aux Terres Australes, 
Pl. 30, fig. 1;—Pyrosoma giganteum LEsSuEUR, Saviany Mém. 1. Pl. 4, 
fig. 7, Pl. 22, 23, Buarnv. Malac. Pl. 83, fig. 6, Cuv. R. Ani., éd. ill., 
Moll. Pl. 133; in the Mediterranean: there is still a smaller species in 
the same sea in which the individual animals are placed in regular circles 
round the cone; Pyros. elegans LESUEUR. 
Family II]. Ascidiw. Apertures of external covering not oppo- 
site, mostly approximate. Branchial sac closed posteriorly. Animals 
either single, or congregated into a common body, affixed. 
