Dr. Hcineken's Description of Cerascopus. 35 



into a denticulate palate, while the broad naked alae 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 half-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. 



Akt. VIII. Descriptions of anew genus of Hemiptera,atid of 

 a species of Hegeter. By C. Hbinkkkx, M.D., ^c. In a 

 Letter to the Editor. 



To THE Editor of the Zoological Journal. 

 Sir, 



The 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 



