194 Mr. Kirby on the Tarsus of Coleoptera. 



by De Geer that the tarsus of Coccinella, usually regarded as 

 trimerous, is really tetrameroiis ; for, speaking of the third or 

 claw-joint, he says : " Cette partie qui a une articulation pres 

 de son origine," &c. ; and this accessary joint he has also 

 figured*. Mr. Spence, in a letter tome dated July 13, 1809, 

 observes that Miiller had discovered this joint in that genus ; 

 and further remarks, " But on examining the Lepturce^ Ceram- 

 hyces, and Chrysomela teiiebricosa, I find (what had escaped 

 Miiller) that the claw-joint of these also has a similar minute 

 joint at the base ; so that if this be allowed to be a true joint, 

 these have in trnxh Jive-jointed tarsi." Mr. Spence, however, 

 did not regard this as a true joint, or one having separate mo- 

 tion. Upon receiving this intimation I made a pretty general 

 examination of tetramerous beetles, and found that the Chry- 

 somelce of Linne in general have this joint, as likewise Curcu- 

 lio L., and others ; I discovei'ed also that it is a true joint, 

 moved by muscles of its own. In consequence the following 

 passage will be found in the third volume of the Introduction 

 to Entomology, some time printed. 



" Pentamerous insects are those which havej'fo^ joints in all 

 their tarsi. This is the most universal, and may be called the 

 natural number of these joints f." 



" Tetramerous insects are those in which all the tarsi con- 

 sist o^four joints ; these in the Coleoptera are next in number 

 to the pentamerous — indeed a very large proportion of them, 

 strictly speaking, ai-e really of the latter description, since in 

 Linne's four great genera, Curculio, Cerambyx, Chrysomela, and 

 Cassida, and some others, the clWiSO-joint {U?igida) consists of 

 two articulations, one very short, forming merely the ball at its 

 base J, which uiosculates in the socket of the preceding joint, 

 and the other constituting the remainder: if you carefully se- 

 parate these two pieces, you will find that the last inosculates 

 in the summit of the ball, and is moved by appropriate mus- 

 cles §. This structure probably permits the readier elevation 

 and depression of this joint ||." 



Mr. MacLeay is too candid, I am sure, to feel any objec- 

 tion to your following the old adage, suwn cuique, on this oc- 

 casion, and giving a place in your valuable Magazine to these 

 remarks. 



I am, dear sir, yours, &c. 



Earham, Wm. KirBY. 



March 15, 1825. 



* De Geer. v. 364. t. xi. f. 6. h. f Introduction to Entomology, iii. 683. 

 % Introd. to Ent. iii. Plate xxvi. fig. 47, 48. d*. § Ibid. fig. 49. s ■ a. 



II Ibid. 684. 



XXXII. On 



