HKSPIRATION — PULMONARY f'lIAMBKR. 
;!(it 
trucks or courses, ])ussiiig through or over tlie gills and leaving the 
body by the exhaleiit aperture. 
Secondary Branch i.e are developed amongst our native species 
only in the Liminvahv, a group which have relinij[uished terrestrial 
life to resume an atpiatic one, and which are even now undergoing 
the process of re-adaptation to the respiration of water, this being 
shown by the diminution or loss 
of the pulmonary cavity and the 
increasing vascularity of the ex- 
sertile, tegumentary appendage 
bearing the anus and known as 
the Auriform lobe ; this new 
organ (jf resj)i ration is now 
aetively functional in Phtuorbh 
Cornells and other species. In 
the marine genera Patelld, etc., 
this re-adaptation has taken 
the form of vascular outgrowths 
within the respiratory cavity, 
but the same result may he attained in other groups by different 
methods. 
Fto Auriform lolteor secondary bram liia 
of I'/anorl>is corncus (li-)i X 12, showing its 
liiglily vascular cliaracter (after Pclscncer). 
alimentary canal, but that of the I’ulmonates is really only a modi- 
fication of the branchial cavity of the a([uatic species, in which the 
'I’lie Pulmonary Chamber of the Pulmonata is not morihologically 
a true luug, as in the Vertebrates, although i)hysiologically performing 
similar functions. The vertebrate lung is a diverticulum of the 
Fifb oOo. — Roof of pulmonary cavity of 
Liniax (L.)» seen from l>elow X 3 
(after Leidy), showing the relationship of 
the lieart and the blood vessels of the lungs. 
a. auricle of the heart receiving the oxy- 
genated blood from the lung plexus; 7'. 
ventricle of the heart ; /r. kidney or renal 
organ ; u. ureter ; r. rectum ; c.o. excretory 
orifice ; r.o. respiratory orifice. 
Fig. oOG. — Longitudinal section through 
mantle of Cyclostoma elcgans (Midi.), highly 
magnified, showing the folds of the vestigial 
branchia (after Oarnaidt). 
