8 
l)i'catliing-liole. These are the gills, consisting of three pairs of simple memhranous (haiitige) leaves. 
He then describes them in detail as to form. 
This appears to he the first published description of the inner gills. 
Brandt’ in 1833 expressed the same opinion as Treviranus as regards the nature of the 
first two pairs of a])pendages in the genus PorceUio. 
I\f ilne-Edwards ^ in 1839 announced that he had confirmed through his own observations 
the conclusions reached by Latreille. He stated tliat the liranched air-canals were rightly to he 
compared with the tracheae and lung-sacs of the Insects and Arachnids. 
The same author in his Histoire naturelle des Crustaces, published the next year, 
says concerning the Cloportides terrestres : “Mais le caractere le plus important . . . est fourni par 
le mode de conformation des fausses pattes abdominales des deux ou cpiatre premieres paires. Ces 
ajipendices servent a la respiration comme chez tons les autres Isopodes ; mais au lieu de constituer 
des hranchies, ils remplissent les functions de poumons, car ils renferment des organes creux dans 
Finterieur desquels Fair atmosphmif|ue penetre directement a travers des ouvertures diversment 
disposees.“ 
A more thorougli study than any hitherto made was that of Duvernoy and Lereboullet 
])uhlished in 1841.® These authors give a detailed account of the general anatomy of the respira- 
tory organs of the land-isopods and also descri))e a series of experiments made upon PorceUio and 
ArmadiUio to determine their comparative vitality in dry and in moist air, in water and when ex- 
])osed to the direct rays of the sun. 
The following is a summary of the conclusions reached by these investigators : 
The external organs are composed of two leaves (the outer of much greater consistence 
than the inner) the space between which has a double communication with the blood system, re- 
ceiving on the one hand blood to he respired and on the other giving hack that respired. 
The “corps hlanc“ is not present in all the Cloportides as Latreilee had announced^ hut 
only in the genera PorceUio and ArmadiUis. In these two genera it is constant in the first two 
pairs of lames operculaires and in two species, PorceUio armadiUoide and PorceUio a trois bandes, in 
all five pairs. 
The corps blanc has a tree like, spongy and vascular appearance. It is a simple modi- 
fication of the lames hranchiales operculaires, through the inward folding and division of the mem- 
hranoiis leaf of the lames. 
It absorbs the moisture of the air and maintains the moistened condition of the lame 
hranchiale [the inner gill]. 
On the posterior borders of the lames enclosing the corps hlanc is a cleft which one of 
the authors had ol)served to dilate and contract and out of wliich they had seen a fluid to pass. 
„I1 s’en echappe, suivant notre observation commune, de tres jmtites (piantites de li(|uide aqueux 
dans lequel du moins, nous avons constate qu’il n’existe pas des globules. “ 
‘ Medizinisclie Zoologie, II. Band, Berlin, 1833, 
L'Institut, 1839. 
* Essai d’nne Monographie des organes de la respiration de I'ordre des Crustaces Isopodes. A nnales des sciences 
natnrelles. Ser. 2, Tom. XV, 1841. 
■* * In this Latreille was followed hy Milne-Edwaeds. See, Histoire naturelle des Crustaces, 
1840. But in his Physio logie Compare e, 1857, he refers to the corps hlanc as present only in the two genera 
named above. 
