Royal Physical Society. 91 



the differences in the form of the joints of the antennae of 

 C. angvstatus, F., and castaneus, St., these are too slight, even 

 adopting absolutely M. Kraatz's own description, to allow us to 

 use them as characters for a species ; but I cannot entirely adopt 

 his descriptions without reservation, as, notwithstanding a very 

 careful examination of the specimens he sent me, I have scarcely 

 been able to detect the differences he alludes to. Turning back 

 to his description, it will be seen that the only differences given 

 are the following : — In C. angustatus, F., he says, the third joint 

 is nearly twice as long as either the second or fourth. In 

 C. castaneus, he says, the third is distinctly longer than either the 

 second or fourth. In angustatus the seventh and ninth are said 

 to be equal in length. In castaneus the ninth is somewhat 

 shorter than the seventh. In angustatus the last joint is said to 

 be " longer than the preceding, long cylindric and acuminate." 

 In castaneus it is " almost twice as long as the preceding, sharply 

 acuminate." The differences here given are thus exceedingly 

 minute, so much so as to be inappreciable by an ordinary ob- 

 server. Now I know that in undisputed species in this genus 

 considerable differences are to be perceived in different indivi- 

 duals in the relative thickness, &c. of the joints of the antennae ; 

 so much so as to make the antennae appear decidedly more 

 clubbed in the one than the other. This minute measuring of 

 the joints appears to me therefore an unsafe character, not to be 

 adopted. There only remains the difference in the form of the 

 posterior trochanters in C. angustatus, F., and castaneus, St. On 

 this I shall only observe, that M. Kraatz admits that there is 

 great variation in the development of these parts, but seems to 

 think there is an impossibility in a transition taking place 

 between a trochanter having a projecting curved tooth at the 

 inner side, and a trochanter itself of a gouge-chisel-shaped form 

 without a tooth on the inner side. My readers must judge for 

 themselves as to this ; but I agree with Erichson in thinking that 

 the development of that part is variable, and I cannot agree with 

 M. Kraatz in putting bounds to the variation. 



The differences we have been considering are almost entirely 

 those between C. angustatus, Fab., and intermedius, Kr., on the 

 one part, and C. castaneus, St., on the other. It is much 

 more difficult to point out those between C. angustatus, F., and 

 intermedius, Kr. : as to these, I shall confine myself to referring 

 the reader to the distinctions pointed out by M. Kraatz himself 

 in his description of C. intermedius above quoted, merely ob- 

 serving that if I am right in joining together the much more 

 dissimilar forms of C. angustatus, F., and castaneus, St., we can 

 have no hesitation in refusing to make another species on the 

 strength of the almost imperceptible differences relied on by 



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