first dages of Pericoma and the Brazilian species. 487 
locomotion. It has some resemblance to the BlepJia- 
rocerid larva of Giirupira, figured by Dr. Miiller in the 
Archivios, etc.^, Eio Jan. iv., Tab. viii., figs. 2, 3; but, 
besides other evident differences, it is flat^ and not roof- 
like like the other. 
Dr. Miiller describes as follows the mode of life of the 
Curupira and Maruina-lsiYY8d (compare above) : While 
the CuTupira-lsbYYSG are fastened to bare rocks, from 
which the waterfalls down perpendicularly, the Marzdna- 
larvae live on rocky w^alls, which, constantly moistened 
by drops of water running down upon them, or by the 
spray of the waterfalls, become covered with a thin, 
slippery, growth of algoe.'" The prime necessity of such 
larvae and pupa3 must be therefore that of clinging to 
their place, and this necessity may perhaps explain the 
development of suctorial discs in both classes of larvse 
[Blepharoceridse and Maruina), as well as the shape of 
the pup^, fitted for adhesion, and therefore flattened, at 
least on one side. These habits appear quite different 
from those of the larvge of P. canescens, as described in 
detail by Prof Miall (pp. 144-146). In case of a heavy 
rain, for instance, which deepens the water and increase^S 
the force of the current, the larva has several alternatives. 
It can cling to the weeds and remain submerged for 
hours. It can leave the water altogether and creep upon 
the wet herbage,'"' etc. When the time of pupation is 
at hand the larva quits the water ; it either burrows into 
the bank, or climbs upon a stone which rises well above 
the water, and there pupates.'^ Such motions, generally 
in a horizontal direction are quicker, and require a 
difi:erent mechanism than a slow, creeping motion along 
a slippery perpendicular surface. 
I should not be surprised that, by using the method of 
catching Maruina-la,rv33 recommended by Dr. Miiller, 
similar larvse should be discovered in Europe. Aquatic 
larvae are often cosmopolitan. 
