482 Mr. Gilbert J. Arrow on Characters and Relationshiin 



preparations I have ascertained that they also are in the 

 normal situation for the Mel olontJiinae, i. e. the three 

 posterior are in the dorsal part of the ventral segments, 

 the sutures of which in this part are still visible. 



Two peculiar genera, Ac! opus and Fhaenognatha, were 

 placed by Erichson in the Glaphyridae, but removed to 

 the MelolonfMnae by Lacordaire on the ground that the 

 situation of the spiracles is of the Pleurostict type. By a 

 preparation of the abdomen of Aclopus hrunneus, I found 

 the spiracles to be completely Laparostict ; but, in a paper 

 published since the present one took shape, Dr. Ohaus 

 (Deutsche ent. Zeits., 1909, p. 427) has made the highly 

 interesting announcement that, while this is so in the 

 male, in the female the four last spiracles are actually 

 situated in the chitin of the ventral segments ; that is, 

 the species is Pleurostict in this sex. All the examples 

 of Phaenognatha and Aclopus hitherto described are males, 

 although Burmeister incorrectly considered both sexes to be 

 represented among the specimens of Aclojms he described, 

 and Lacordaire's account shows that, in spite of his state- 

 ment as to the spiracles, he knew only the male. The 

 female is wingless and clumsily built, and there is little 

 doubt that this is the case in both genera, and that, as in 

 Pachypns, all the females are very retiring and inert. Dr. 

 Heller considers the group to be rather closely related to 

 Pachypus ; but although I believe all agree in being near 

 the primitive Lamellicorn stock, it is likely that the 

 resemblance is in part due to similarity in the mode of 

 life. There are wide differences in the structure of the 

 antennae and head, and the greatly exserted labium and 

 mandibles connect the Aclojmiae with the Geoirupinae and 

 allied groups. There is certainly no special affinity with 

 either the Glaphyrinae or Melolonthinae, and the propriety 

 of regarding them as an independent and rather isolated 

 sub-family can hardly be questioned. 



An interesting feature of the genus Adopus, and, no 

 doubt, a primitive one, is the existence of apparently 

 sensory hairs upon the dorsal surface of the prothorax. 

 This is perfectly free from hairs, except for one or two 

 long ones standing upright on each side and arising from 

 a couple of small pits, one on each side of the middle. 

 These pits are always visible, even when in roughly-used 

 specimens the hairs have been lost. Somewhat similar 

 hairs are found on the head or thorax in certain Carabidae 



