MR. CURTIS ON HYPOCEPHALUS, A GENUS OF COLEOPTERA. 235 



that I was led to make some changes which I shall correct on the first opportunity. Indeed 

 if we were to reject the form of the feet in the Coleoptera, disregarding the number of 

 the joints, the Heteromera might be distributed throughout the entire mass. 



I must not, however, be misunderstood regarding the value of the structure of the 

 mouth in the formation of systems, for although it may be subject to great modifications, 

 and depart from the typical forms, like the changes in the tarsi, such anomalies are perhaps 

 confined to the minuter members of a family, and a comparison of the trophi is unques- 

 tionably of the greatest importance in arriving at the true affinities of insects. As our 

 materials multiply our knowledge advances, and changes become necessary and unavoid- 

 able, but let them be made on substantial grounds, not losing sight of the first principles 

 of true affinity. 



I trust that those from whom I differ in opinion will be assured, that it is from no love 

 of opposition that I have ventured upon this difficult subject, but with the sole desire of 

 arriving at the truth, and to assist in fixing our Systems on some firm basis, generally 

 understood, and universally to be adopted, so that we may no longer be tossed to and fro, 

 as we are at present ; every new work, unscrupulously changing, sometimes entirely 

 reversing or disregarding, the labours of the most profound and learned men of science, 

 that have adorned the pages of Natural History. 



EXPLANATION OF THE PLATE. 

 Tab. XXV. 



Fig. 1. exhibits the under side of Hypocephalus armatus, mas ? a little larger than Mr. Turner's specimen ; 

 a. the antenna ; m. the mandibles ; p. the palpi, the central pair being the labial, inserted at the 

 margin of the trilobed mentum. Between the base of the head and the antepectus is shown the 

 large membranous triangular cavity, enclosed on the sides by a series of broad teeth (s). At the 

 base are inserted the 1st pair of legs, with short, slightly dilated tarsi; a lobe passing between 

 the coxae, dilated at the apex, keeled down the middle (a. p). The ample postpectus follows 

 (p.p), near the base of which the 2nd pair of legs is inserted, with much longer tarsi, and at 

 the hinder margin the 3rd pair of legs, with enormous thighs, curved tibiae, and perfect speci- 

 mens exhibit 5-jointed tarsi similar to the 2nd pair, but the basal joint is shorter. Fig. b. is the 

 small attenuated abdomen. 



Fig. 2. Upper side of head, showing the spreading lobes at the base (b) ; a. basal joint of antenna ; /. lateral 

 lobes of the head ; m. the mandibles ; e. the eyes. 



Fig. 3. The insect in profile ; a. the antenna ; I. lateral lobes of the head ; m. the mandibles ; p. the palpi ; 

 e. the eye ; s. the serrated or toothed margin of the antepectus. 



Fig. 4. Antenna magnified. 



Fig. 4*. The trilobed broad mentum ; p. the triarticulate palpus. 



Fig. 5. Four basal joints of the anterior tarsi magnified. 



To illustrate this subject as far as I am able, I have added figures of the trophi, &c. of Cyr- 

 tognathus rostratus, Fabr. 



2l2 



