Dr. Heineken’s Description of Cerascopus. 35 
into a denticulate palate, while the broad naked ale are reflected over the 
singular organs which supply the place of the under jaw of the Mamma- 
lia. The inferior portion is folded into a haif-closed tube, resembling 
the trachea of birds, from the two lines of external sloping parallel ten- - 
dons, which give motion to each molar tooth-like process, as they are set 
in action to grind the food and pass it into the stomach. The tongue is 
minute, lobate at the tip, and terminates this singular organ, to which 
the name of Trachyderma is now given. We easily see why the termi- 
nation is not closed into a perfect tube, as this structure would have in- 
terfered with the necessary degree of motion required for the teeth. In 
other Mollusca the organs I have called Siagonia, from their use, are 
often quadrate cartilaginous bodies; here they are represented by two 
large elongate bladders, composed of a white tough skin, and most tightly 
distended with a transparent fluid, so as to give them almost the strength 
of cartilage. Their bases are distant, while the apices are brought toge- 
ther under the alate processes of the palate, and set in motion by an ap- 
paratus of strong and numerous muscles, as we see in the very satisfactory 
outlines given by Cuvier. 
I hope soon to have opportunities of publishing, in some work or 
other, figures of the many beautiful species which inhabit the Caribean 
Sea. 
St. Vincent, May 1, 1829. 
Anv. VIL. Descriptions of anew genus of Hemiptera, and of 
a species of Hegeter. By C. Huinuxen, M.D., &c. Ina 
Letter to the Editor. 
To THE EprTor OF THE ZOOLOGICAL JOURNAL, 
Sir, 
Tue first of the two following insects appears to me to have been 
hitherto undescribed, and to constitute an intermediate genus between 
Ploiaria and the section Ploteres of the “Genera, &c.’’ of Latreille; 
and the second to be a new species of his genus Hegeter. As, however, 
c 2 
