IV A REVIEW OF THE GENUS THYCE AND OF THE 

 NORTH AMERICAN SPECIES OF POLYPHYLLA. 



No systematic revision of Thyce Lee., has ever been published. 

 Only two species were known to Dr. G. H. Horn palpalis Horn and 

 carpenteri Lee. and these were both assigned in error to Plectrodes 

 Horn. The American species of Polyphylla were last reviewed by 

 Horn (Tr. Am. Ent. Soc., 1881, p. 73)* in a short article, but the 

 forms then known were only about a fourth as numerous as the 

 species and subspecies which now lie before me. The object of 

 the present study is to attempt as orderly an exposition of all the 

 available material in these two genera as may be possible. This 

 material has been accumulating gradually from many sources 

 through the past thirty years and is tolerably complete. 



There are four Melolonthid genera, including the two mentioned 

 above, which form a natural group in our fauna; they have 10- 

 jointed antennae, the last spiracle in the dorso-ventral suture and 

 more or less unequally toothed tarsal claws and may be known 

 among themselves as follows: 



Abdominal segments (d 71 ), excepting the last, closely connate and im- 

 mobile 2 



Abdominal segments (cT) all perfectly free 4 



2 Antennalclub 6 or y-jointed, very long and outwardly recurved (cf), or 

 short and straight (9); last joint of the maxillary palpi small, 

 slender, cylindroidal, nearly similar in the sexes, not excavated 

 though generally narrowly flattened anteriorly in the male; elytral 

 ornamentation vittate or tending thereto; ungual dentition but 

 slightly unequal; abdominal segments, except the last, always 

 connate in both sexes Polyphylla 



Antennal club 3-jointed, last joint of the maxillary palpi differing greatly 

 in the sexes, very much larger and deeply excavated in the male; 

 ungual dentition decidedly unequal and dissimilar 3 



3 Antennal club (cf ) long, outwardly recurved distally as in Polyphylla, 

 the last two joints of the funicle lamellately prolonged anteriorly to 

 some extent; elytral vestiture vittate in arrangement also nearly 

 as in that genus; female unknown Dinacoma 



* This is a short paper of about three pages, drawn up very hastily and superficially 

 and containing several misidentifications, as well as errors relating to habitat. The 

 author has throughout used the word trisinuate in referring to the clypeus, instead of 

 bisinuate, which was doubtless the term intended. 



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