94 PSYCHE [October 



them in such entomological literature as was accessible. The mouth parts of the 

 Coleoptera having been so much used in classification I could scarcely believe that 

 these were undescribed, yet I have not discovered any mention of them. ■ 



Maxi/lae\\z.ve. the same parts as in the larva, though more highly differentiated. 

 The edge of the lacinia is covered with a dense fringe of hairs. The galea is four 

 jointed and the palpus is wanting. 



The labiian ( Plate IX, fig. 19) is quite different in its shape from that of typ- 

 ical Coleoptera. The sub-mentum is long and broader at the middle than at the 

 ends. The mentum is of about the same length but more slender.. The para- 

 glossa is short and widens at the anterior end beyond which a long narrow glossa 

 projects. Both are tipped with numerous small spines. The palpi are small and 

 simple. 



The Hypopharynx is well developed, at least in Mononychus (Plate IX, fig. 

 14, //>■), with a free tip and covered with recurved prickles. 



The inusclcs which move mouth parts lie in the more convex part of the head 

 in very much the same positions as in the larva. The tendons which are there 

 either short or altogether wanting, have developed with the rostrum. They lie 

 upon the ventral side and connect the muscles in the head proper with the append- 

 ages at the apex. (Plate IX, fig. 14, /.) 



The antennae are situated upon the beak from one to two mm. from the more 

 convex part of the head. The scape is very long. The slender pedicel has seven 

 segments. The ovate club consists of three or four, more or less, consolidated 

 segments. 



Two sets of muscles move each antenna. Their fibers originate in the ten- 

 torium and shortly unite into four uniformly thread-like tendons which are inserted 

 upon the round basal piece of the scape; two, probably used for making the for- 

 ward movements, upon the inner side ; and two, which make the opposite back- 

 ward movements, upon the outer side (Plate IX, fig. 14, am. and ant.). 



The Shifting of Mouth Parts in Balanixus. 



The relative positions of mouth parts dift'er considerably in these two species. 

 In Mononychus the order is that of normal Coleoptera. During the metamorphosis 

 of Balaninus, however, a curious shifting in positions of mandibles and maxillae 

 takes place. The exterior sides of the mandibles turn ventrally, approximating the 

 normal positions of maxillae. The maxillae, in turn, are pushed dorsally between 

 mandible and mouth, the brush-like edges of their laciniae protruding between man- 

 dible and labrum. The mandibles then move vertically as described by Dr. Horn 

 (Amer. Philos. Soc. Trans., p. 457, 1873), who conceived them as working upon 

 each other like the blades of a pair of shears. 



