14 INSECTA. 



gated cone ; the intermediate joint of the club entirely enveloped by 

 the two others, as in the last subgenera ; the tibiae narrow and elon- 

 gated ; the epistoma rounded anteriorly *. 



AcANTHocERUs, Mac Leay. 



First joint of the antennae very large, dilated superiorly and lami- 

 niform ; the edges of the intermediate leaflet of the club, when it is 

 bent, are exposed. The tibiae, the four last particularly, are lamel- 

 liform and cover the tarsi, folding over them when the leg is con- 

 tracted. The epistoma tapers to a point or terminates in an angle. 

 The thorax is almost semilunar f . 



There, or in our second division of the Arenicoli — Trogides, Mac 

 Leay — the antennae, scarcely longer than the head, are always com- 

 posed of ten joints, the first of which is large and very hairy. The 

 ligula is entirely concealed by the mentum. The labrum and man- 

 dibles are but little exposed, and the latter are thick. The palpi are 

 short. The mentum is entirely pilose. The inner side of the max- 

 illae is armed Avith teeth. The cinereous or earth-coloured body is 

 very scabrous or tuberculous above. The head is inclined, termi- 

 nates in an angle or narrows to a point. The thorax is short, trans- 

 versal, without a lateral border, sinuous posteriorly, Avith projecting 

 anterior angles. The abdomen is large, arched, and covered with 

 very hard elytra. The anterior legs advance, and their thighs cover 

 the under part of the head. These Insects produce a stridulous noise 

 by the reiterated and alternate rubbing of the pedicle of the meso- 

 thorax against the internal parietes of the thoracic cavity. 



They are found in earth or sand, and appear to gnaw the roots of 

 vegetables. They form the genus 



Trox, Fab., Oliv. 



From which, under the generic name of Phoberus, M. Mac Leay, 

 Jun., has separated those in which the sides of the thorax are de- 

 pressed, dilated and bordered with spines, and Avhich are destitute of 

 wings. On each side of the posterior edge of the thorax is a deep 

 emargination ; the epistoma is rounded anteriorly J. 



* Hor. Entom., I, 1, p. 120 ; Geotmpes orator, Fab. 



-f- Mac Leay, lb. p. 136 ; A. eeneus, a species for tlie knowledge of which I am 

 indebted to one of our most able naval engineers, and not less excellent entomolo- 

 gist, M. Lefebure de Cerisy. M. Mac Leay refers the Trox spinkornis, Fab., to the 

 same genus. 



:|: Trox hor ri dm, Fab.; Mac Leay, Hor. Entom., I, 1, p. 137. The species of 

 Trox, Fab., remain where they are. See this author, Olivier and Schcenherr. 



The genera Cryptodus and Machidius, arranged by Mac Leay in his family of the 

 Trogidae directly after that of Phoberus, have the posterior extremity of the abdomen 

 exposed, and nine joints in the antennae, characters which appear to remove them 

 from Trox. I suspect that the Machidii, from the form and emargination of the 

 labrum, and from some other chart-xcters, are allied to the Melolonthse. The Cryp- 

 todi are distinguished from all other Scarabaeides by their mentum, which almost 

 completely covers the mouth beneath, and even by the labial palpi, situated, as well 

 as the ligula, behind it. These two genera are established on Australian insects 

 •which I have not seen. 



