214 
Dr. Kidd on the 
cylinder, passing into a cone towards the anterior part : the 
upper portion and the sides, which are covered with a re- 
markably smooth down resembling the finest velvet, form a 
homy case of considerable thickness and strength ; which 
contains, or, more properly speaking, is almost entirely occu- 
pied by the very large and powerful muscles which move 
the fore-legs. It is divided longitudinally into two equal 
parts by an almost bony septum of a complicated form : this 
septum upon the whole bears an obvious resemblance, but 
in an inverted position, to the deep sternum, together with the 
furcular clavicle of birds, and is destined indeed to a similar 
use ; to give attachment to the powerful muscles which are 
to move the anterior extremities. It differs however from the 
corresponding part in birds in two considerable points. It 
differs, first, in consisting of two laminae instead of one : these 
lamina are parallel to, but distinctly separated from each 
other, so as to give passage to the esophagus, and room for 
the attachment of muscles which assist in moving the adja- 
cent parts. It differs again from the sternum of birds by 
having a very hard spine, which resembles a common thorn, 
attached to the inferior and posterior edge of the furcular 
bone, and passing rather obliquely downwards and back- 
wards. This process serves for the attachment of numerous 
muscles which adhere very firmly to it, and are inserted on 
either side of the commencement of the abdomen ; enabling 
the animal to bend its thorax to an angle with the abdomen, 
a posture which has already been described as very charac- 
teristic of this insect. 
From the under part of the thorax and near its posterior 
extremity arise the two fore-legs ; those singular instru- 
