458 PROCEEDINOS OF THE NATIONAL MU8BVM. vol.46. 



Some of our American specimens have the clear yellow body color 

 of the typical European flavescens, but as a rule the color is ocher 

 yellow or buflf or cream yeUow. Before the scales are removed the 

 insect is lead-colored. As a rule, the antennae are shorter than the 

 body. I have, however, from Georgia, a single specimen of unusual 

 size (length 6 mm.), in which the antennae are longer than the body, 

 in the ratio of 8: 7, and curl at the ends. 



The number of intermediate teeth on the mucro ranges from five 

 to twelve in specimens 2.5 mm. or more in length, with an average of 

 seven or eight. The unguiculus is usually one-toothed, and on the 

 largest specimens a small second tooth may be present. 



The prevalent American variety, with tridentate ungues (pi. 40, 

 fig. 1), is the form that I have been referring to, in correspondence, 

 under the name of separatus. 



From the original descriptions one might infer that T. flavescens 

 Tullberg, T. americanus Schott, and T. arcticus Schott were three 

 different species. Sucli is not the case, however, as I have already 

 pointed out. (Folsom '02, p. 97-102.) In Alaska the three forms 

 intergrade in one and the same locality; though in most other parts 

 of the United States the three are fairly distinct. Flavescens is, for 

 purposes of nomenclature, the typical form, with separatus, ameri- 

 canus, and arcticus as its varieties, and these forms may ordinarily 

 be distinguished as follows: 



Key to forms of Tomocerus flavescens Tullberg. 



One or two lai-ge dental spines at the proximal end of the series. 

 One large proximal spine: 



Teeth of unguis 2 T. flavescens, typical form. 



Teeth of unguis 3 T. flavescens, var. separatus, new variety. 



Two large proximal spines ; teeth of unguis 3 or 4 . T. flavescens, var. americanus Schott. 

 No large proximal dental spines; teeth of unguis 4, rarely 5, var. arcticus Schott. 



This table refers to large specimens (2.5 mm. or more in length) ; 

 in small specimens there are fewer teeth on the large claws and fewer 

 spines on the dentes. 



Synonymy. — TuUberg described flavescens in 1871 and 1872, and 

 all the European authorities know what form he meant. His 

 description, being the first adequate diagnosis of the species, should 

 be accepted in the interests of stabiHty. Several writers, however, 

 have tried to supplant flavescens with previous names, based on 

 insufficient descriptions, to the confusion of the nomenclature. The 

 name used most often to supersede flavescens has been niger of 

 Bourlet ('39, p. 390), whose description of Macrotoma nigra is as 

 f oUows : 



Mdme longueur que la pr^c^dente pour le corps et les antennes; corps ecu vert 

 d'^cailles noires, offrant ^ la vue simple un l^ger reflet argent^. Corps d6pouill6 de 

 sea ^cailles, pr6sentant une couleur d'un jaune de cire. Bord ant^rieur du thorax 



