April 1889.] 



rSYCI/E. 



195- 



represents a first pair of antennae. The 

 lack of traces of a sutnre in the epi- 

 pharynx corresponding to the labral su- 

 ture above, suggests that the labrum does 

 not represent a pair of coalesced appen- 

 dages, and that it, with the clypeus, sim- 

 ply forms the solid epidermal roof of the 

 mouth. 



The only soft structures seen between 

 the epipharynx and labrum besides the 

 nerves of special sense, are the elevator 

 muscles of the labrum and two tracheae, 

 one on each side. 



The structure and armature of the 

 epipharyngeal surface even, besides the 

 taste-pits, cups and rods, is unexpectedly 

 varied, the setae assuming very diflerent 

 shapes. There seems to be two primary 

 forms of setae, (i), the normal forms 

 which arise from a definite cell, the 

 setae being a hypertrophied nucleus, as 

 first shown by Newport, and (2), soft, 

 flattened, often hooked hairs which are 

 cylindrical toward the end, but arise 

 from a broad triangular base, without 

 any cell-wall, not arising from distinct 

 nuclei. These are like the gathering 

 hairs (Cheshire) on the bee's and wasp's 

 tongue ; they also line the walls of the 

 pharynx and extend toward the oesopha- 

 gus. They are the "hooked hairs" of 

 Will. The first kind or normal setae 

 are either simply defensive, often guard- 

 ing the sense-cups or sensorv fields, or 

 they have a nerve extending to them and 

 are tactile. 



It will be seen by the following de- 

 scriptions that in the thysanura no true 

 gustatory cups or pits have been found ; 

 and that immature dermaptera are des- 



titute of them. On the other hand taste, 

 cups occur on the epipharynx of the lar- 

 vae of longicorn, scarabaeid and bu- 

 prestid beetles, and they are as abun- 

 dantly developed in carabid or car- 

 nivorous beetles as in plant-eating cole- 

 optera. Also, within the limits of a 

 familv like the locnstidae they are less 

 abundant in one of the more general- 

 ized genera as XiphidiitDi^ and more nu- 

 merous in a highly specialized genus, as 

 CyrtophyUus. 



I should say that I have examined the 

 taste-cups of the honey bee, finding that 

 they agree with Wolfl's figures, and that 

 those of insects of the orders described 

 below are essentially of the same struc- 

 ture and all seem by situation to be gus- 

 tatory in function. 



Order Thysanura. 



LepisDia sp. from Havana. — The 

 specimen examined was one of a number 

 kindly collected for me by the venerable 

 Professor Poey of Havana in his own 

 house. The labrum is slightly excavated 

 along the entire margin, but there is no 

 trace of a median suture ; and over the 

 surface, are scattered long acute hairs, 

 while at the base and over the clypeus 

 are thickly planted, singular long setae 

 which arc hairy beyond the middle, and 

 are forked at the end. 



The epipharynx ends in front in a 

 broad median lobe somewhat as in For- 

 Jiciila, the edge of which bears numer- 

 ous very short cylindrical rods, whose 

 presence can only be distinctly made 

 out by a power of 400 diameters. This 

 lobe is also covered with an exceedingly 



