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XIII. On the Arrangement of the Cutaneous Muscles of the Larva of Pygæra bucephala. 
By JOHN LUBBocK, Esq., F.R.S., F.L.S., F.G.S. $c. 
* i Read February 18th, 1858. 
LYONET'S celebrated memoir on the larva of Cossus ligniperda, and Straus-Dürckheim’s 
still more beautiful work on Melolontha vulgaris, are the most perfect, and indeed the 
only monographs we have at all complete, on the general anatomy of any insects. 
The very complicated arrangement of the cutaneous muscles in the caterpillar of Cossus 
inspired me with the wish to see how far the muscles of other larvæ would agree with, or 
differ from, this type. 
With this view I dissected with great care some larvæ of Tipula oleracea and of 
Ctenophora bimaculata; but on comparing two or three specimens together, I found to my 
astonishment very considerable variations. It-then occurred to me to compare several 
specimens together, in order to ascertain the nature and amount of these variations. The 
larvæ, however, of the different species of Tipulidæ so much resemble one another, that I 
could not feel certain that these supposed variations were not rather specific differences. 
In order to remove this element of doubt, I selected the larvæ of Pygera bucephala, 
which were obtainable in any numbers, and could not be confused with those of any 
other species. Moreover, as some of these caterpillars live on oak- and some on beech- 
leaves, I was curious to observe whether this difference in the food induced any alterations 
in the muscles. It did not, however, appear to have any such effect. > c 
The full-grown caterpillars are about two inches long, and of a brown colour with dark 
longitudinal bars. DE : 
I have divided my paper into three sections :— 
First, a description of the cutaneous muscles of the larva of Pygæra. 
. Secondly, a description of the variations observed in these muscles ; and : 
Thirdly, a comparison, as complete as possible, of these muscles in Pygera with the 
corresponding muscles of other larvæ. : : 
In examining closely Lyonet’s drawings, I have always found them inconveniently 
small: moreover he has represented alternately the two sides of the insect, so as to reverie 
the directions of many of the muscles; and as he has also figured the same muscle in dif- 
ferent plates, it is difficult to ascertain the exact number of muscles in each segment. 
` In my drawings I have always represented the left side of the insect, and hayo never 
introduced the same muscle into two plates. — — eh 
I propose to commence my description of the muscles at the third abdominal segment, 
and then, passing forward on the one hand and backward on the other, to point out the 
differences which exist in the muscles of the anterior and posterior "o à 
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