174 Mr. W.S. MacLeay on the Anatomy of the 
“ prosternum’’ is a “ longitudinal or other elevation of the antepectus 
** between the fore-feet.”” I conceive therefore that he gives the name 
of prosternum only to that part of the sternum of the prothorax in a 
Polistes which resembles the escutcheon, and that he would call all the 
rest part of the antepectus. 
2. The antefurca is considerably developed, the middle process be- 
ing connected with the sternum and the lateral process with the epimeron ; 
the interval forming part of the acetabula of the fore feet.* 
_ 3. The two episterna are each very large, and occupy great part of 
the antepectus. These pieces, together with the epimera, form the ante- 
pectus of Kirby, who has not distinguished. between them.T 
4. Ths two epimera are situated above the antepectus, are smaller 
than the episterna, on which they rest, and are connected together above 
by a ligamentous membrane, which is the representative of the horny 
shield of the prothorax in Coleoptera. 
2. OF THE PECTUS OF THE MESOTHORAX. 
1, The sternum of the mesothorax is large and broad, occupying the 
whole front of the medipectus except for a small space at the two upper 
angles. It is therefore somewhat of a quadrate form.§ The peristethium 
of Kirby in Hymenoptera is the fore part of the sternum, this author not 
dissecting the pieces according to their sutures,|| and therefore confining 
the name of mesosternum to only that part of the sternum of the meso- 
thorax which is between the legs. 
2. The medifurca is very beautiful, exactly resembling the Greek 
letter Y with its arms joined by a cross line. 
3. The episterna of the mesothorax are two sub-triangular pieces, the 
three sides of which are bounded by the collare or scutellum of the pro- 
thorax, the sternum and the epimeron of the mesothorax.** The wings 
are inserted at one of the angles of these lateral sub-triangular pieces, 
* Fig. 8, Z. + Fig. 8, I. 
{ Fig. 8, A. § Fig. 9, Q. 
|| It may be proper, however, to observe, that although the pieces are here 
confluent, each pectus contains typically four pieces to its sternum. 
q Fig. 9, Y. ** Fig. 9, S. 
