THE CANADIAN ENTOMOLOGIST. 251 



entirely lost in piscatrix. A comparison with the mandibles of Hcemonia 

 and Crioceris brings out this degeneration quite clearly. 



The maxillse are very highly specialized and entirely different from 

 those of any other Chrysomelidse. The cardo is unusually large (.15 

 mm.), being nearly one-half the whole length (.35 mm.), while the stipes 

 is proportionately shorter. The palpus consists of the usual four seg- 

 ments, which are but obscurely defined ; is rather stout, and between .15 

 and .2 mm. long. But the most peculiar feature of the maxilla is the re- 

 lation of the lacinia and galea. In most Chrysomelid larvae the lacinia is 

 rudimentary or merely represented by a stout chitinous process, or spine, 

 at the inner base of the galea, though in many of the Gallerucini and 

 others it is as large or larger than the galea. Usually the galea is com- 

 posed of a large curved sclerite, articulated to the stipes just mesad of 

 the palpus, with its outer face on the under side of the maxilla, but so 

 curved that at its tip it is concave on the mesal side, appearing like a 

 hood to the small lacinia, and surmounted by numerous stiff setse. In 

 Donacia the galea seems to have faced around until its concave inner face 

 opens directly ectad. It is surmounted by a long thin concave, trans- 

 parent process, nearly the length of the last three segments of the palpus, 

 being either a single highly specialized seta, or a number of them grown 

 together. The inner chitinous margin of the stipes is decidedly produced 

 at the base of the lacinia. From it project two chitinous bands nearly to 

 the tip of the galea. At this point it is articulated to them by a socket 

 joint, a long, stout, concave, chitinous, sword-like process, about .1 mm. 

 long, which is encased within the sheath-like process arising from the 

 galea. Between the chitinous bands forming the anterior margin, the 

 base of the lacinia, and the galea, is a hollow space. At the apex of this, 

 just below the articulation of the two processes, is a small oval mass, 

 whether muscular or chitinous I am unable to determine, which seems to 

 be connected to the base of the chitinous bands of the anterior margin. 

 In the cavity of the inner chitinous process are seen two slender, whitish 

 filaments or threads, and though they could not be traced for their entire 

 length, they seem to arise from this oval mass, immediately below. The 

 most plausible explanation of the use of this curious contrivance seems to 

 be that it is used for piercing the tissues of the food plants, though this is 

 entirely a matter of conjecture. 



The labium is rudimentary, and the palpi are mere papillae of a single 

 segment .02 mm. or .03 mm. in length, with no trace of another segment 



