8 
BRITISH BEETLES. 
resemblance to that of Amphioxus and through this 
genus to that of the lower Vertebrates; in their perfect 
state the Ascidians would not be supposed to occupy 
at all a high position, being barrel-shaped or sac- 
shaped animals, with the body completely surrounded 
by a gelatinous or cartilaginous mantle; the Tuni- 
cata are all marine, and some of them are strongly 
phosphorescent. 
The Cephalochorda are distinguished by having 
“no paired limbs; no skull or vertebral arches ; no jaw 
arches; no differentiated brain, sympathetic nervous 
system, or organ of hearing ; no heart, spleen, kidneys, 
or sexual ducts ; ” the notochord, which answers to 
the backbone of the Vertebrata, extends from nearly 
one end of the body to the other ; there is but one 
genus contained in the group — Ampliioxus — with 
species found near the coast in various parts of the 
world. The animal, when adult, lives buried in the 
sand with the mouth aperture just exposed. ( Vide 
Rolleston’s “Forms of Animal Life,” 2nd edition, p.437.) 
The members of the last division of the Animal 
Kingdom, the Vertebrata, are characterized by the 
possession of an internal skeleton, which is bony or 
cartilaginous ; dorsal processes of this skeleton enclose 
the nervous centres (the brain and spiual chord), and 
ventral processes (ribs) enclose the cavity containing 
the heart and lungs ; two pairs of limbs, at least, are 
present ; the nervous system, and the various systems 
of circulation, digestion, respiration, &c., are developed 
in a greater or lesser degree of perfection ; in a work 
like the present there is no need to discuss the various 
sections of this the most important division of the 
Animal Kingdom. 
