70 Mr. W. S. Macreay on the Structure of the Tarsus 
three very natural groups is, that it consists of five articulations, 
of which the three first are dilated into cushions, the third being 
bilobed, while the two last are filiform, the fourth being very 
small. But if these insects be thus pentamerous*, our attention 
will naturally be turned to the Trimera of the French school. 
May not they also have erroneously been described? Latreille, in 
characterizing the well-known genus Coccinella in Deterville's 
Dictionnaire d' Histoire Naturelle, says, “Trois articles aux tarses 
dont les deux premiers en cceur et garni des brosses.” Yet on 
examining the Coccinella 19-maculata of Java, we clearly see 
that it is at least tetramerous, the two first joints of the tarsus 
being dilated, and the two last filiform. De Geer has even given 
a correct magnified figure of a similar structure of the tarsus in 
* On this paper being read before the Linnean Society, a short notice of its general 
purport appeared in the Philosophical Magazine for February last; and Mr. Kirby 
having seen this notice, stated in the following number that he was aware of the facts 
given to the public in my paper. "To this effect he quoted a passage from the forth- 
coming third volume of his Introduction to Entomology. However, in a subsequent 
communication inserted in the Philosophical Magazine for April, and intended to cor- 
rect some mistakes of the former communication, Mr. Kirby, in speaking of the joint of 
the tarsus in Coccinella figured by De Geer, but certainly not understood by that great 
naturalist, says, * He (i.e. De Geer) regarded this joint not as a primary but as a secon- 
dary joint, or the joint of a joint, as I am disposed to do myself, and therefore, in the 
Introduction to Entomology, and upon other occasions, I speak of the Chrysomelida, &c. 
as tetramerous, and the Coccinellidæ as trimerous.” As Mr. Kirby thus continues to 
consider the Chrysomelide, &c. as tetramerous, and the Coccinellide as trimerous, and 
has thus abandoned all claim to that generalization upon which the whole use and 
merit of this discovery, as I conceive, hinges, I have only to say, that I have not been 
able to discover with him that Cassida has the same kind of tarsus as Cerambyx or 
Chrysomela. In the above-mentioned passage, cited from the forthcoming volume of 
the Introduction to Entomology, Mr. Kirby says, that in the Linnean genera Curculio, 
Cerambyx, Chrysomela, Cassida, &c. “ the claw-joint consists of two articulations.” 
Judging from the affinity of Cassida to Chrysomela, I thought so myself at first, but I 
certainly have not been able to confirm this reasoning by observation.— May 1825. 
his 
