326 Notice of Chiasogndthia Grdntiu 



front of which arises a narrow transverse immovable plate, 

 with the sides rounded (which, from the analogies existing 

 between the structure of this insect, Z/Ucanus, ik/elolontha, 

 <jeotrupes, Carabus, &c., I consider as the stirpes of the 

 mentum, and which, in iucanus, is much more developed, and 

 broader in front). The true chin, or mentum, I consider to 

 be represented by the semicircular plate, notched in front, 

 which here, nevertheless, performs the true office of a lower 

 lip, by closing the mouth. In addition to the three-jointed 

 palpi, and their broad internal scapes, there only remain 

 to be discovered the true lower lip (labium) and tongue 

 (lingua). Now, in the English stag beetle, as in this insect, the 

 bases of the scapes of the palpi are united by a fleshy tubercle, 

 which, in the former insect, is adapted to a small notch or 

 incision at the base of the mentum within ; we can, however, 

 scarcely consider this tubercle as the lower lip : whilst the 

 only other part of the instrumenta labialia remaining unnoticed, 

 are the two long and delicate central plates, employed, in con- 

 junction with the maxillary plates, in lapping up sap, as above 

 stated, which must consequently be considered as representing 

 of themselves both the lower lip and tongue; and, from the 

 analogies above pointed out, I cannot but consider that we are 

 warranted in regarding the outer surface of these plates as 

 representing the labium, and their inner surface the tongue. 

 Hence, we shall be enabled to consider the palpi as truly 

 belonging to the lower lip ; or, perhaps, rather as arising 

 between the chin and lower lip ; which I apprehend to be the 

 typical structure of the Coleoptera. The membranaceous 

 plates of the lower lip are of a much more delicate structure 

 in this insect than in Z>ucanus, as well as much more elongated, 

 so as admirably to perform the office of a tongue : it also 

 appears to me that, when alive, they are flat, and not curled 

 at the sides, as they now appear in their dried state.* 



Respecting the affinities of this insect, which is evidently of 

 the male sex, the nearest approach to it is evidently made by 

 the South American genus Pholidotus. Indeed, in the structure 

 of the lower jaws and instrumenta labialia of the two genera 

 (if we except the coat of down with which the mentum in that 

 genus is clothed) there is very little difference. The latter 

 genus is evidently allied to Lamprima, and these three genera 



* Any one who will take the trouble to cut off the large plate which 

 closes the under side of the mouth of a stag beetle will be able to verify 

 some of the preceding details, and will thereby be enabled much more 

 readily to underytand the subject. 



