466 Proceedings of Philosophical Societies. (Junn, 
of Latreille. It has at the base of the abdomen an elevated horn, 
going forwards as far as the head, where it terminates by a bend 
back. M. Latreille has ascertained that this horn is the sheath of 
the wimble, an instrument with which many other hyrnenoptera are 
furnished, but which is usually differently placed. ‘The base only 
of the wimble of the diapria is contained in its horn ; but the point 
issues, as usual, from the anus. 
M. Latreille has given us a very detailed description of certain 
-erabs of the Mediterranean, very remarkable from having their 
eyes placed, not, as in the ordinary crabs, upon a single moveable 
articulation, but upon a long tube with two articulations, so that 
the animal moves them like the branches of a telegraph. Their 
hind feet are placed upon the back, like those of the dorippes. 
Some of these crabs had been already observed by Rondeletius and 
Aldrovandus, but these ancient naturalists did not mention the sin- 
gular structure of their eyes. M. Latreille forms them into a genus, 
under the name of Aippo-carcinus. Almost at the same time Dr. 
Leach, a skilful English naturalist, who is occupied with a great 
work on crustaceous animals, described these species under the 
generic name homolus. F 
M. Savigny has established last year, by many observations, an 
analogy of structure much greater than was supposed between the 
mouths of winged instruments, whether suckers or masticators ; 
and he has shown that the sheaths of the suckers, trumps, and 
other instruments of deglutition of the first, and sometimes these 
instruments themselves, may be considered as prolongations of some 
of the palpz and jaws of the others. He has presented this year a 
great work, from which result analogies of another order, between 
the mouths of the ordinary masticators and those of certain genera 
which appeared anomalous, some of which have been arranged 
among crustaceous animals, and others among insects without 
wings. 
Naturalists had remarked for a long time that a part of the jaws 
of these genera with extraordinary mouths resembled feet, and M. 
Savigny endeavours to prove that they are really feet, which, 
assuming more or less the form and the functions of jaws, join 
themselves to the jaws properly so called, or even take their places 
altogether. 
Thus in the scolopendre there exist two sorts of supernumerary 
lips, of which the outermost have strong, hooked palpe, which 
serve the animal for seizing his food. M. Savigny observing that 
they are not connected with the head, but with the first ring of the 
body, considers them as the first two pair of feet metamorphosed. 
In the crabs, in which the head and corselet are confounded 
together, the supernumerary jaws are evidently the first feet; fre- 
quently their form even, as in the squille, is pretty evident. But 
in these animals, and in several others, whose mouth the author has 
described with infinite attention, there always exist ordinary jaws. 
On the other hand, in gnagric scorpions, and other genera without 
