NO. 2037. NORTH AMERICAN SPRINO-TAIL^—FOLSOM. 457 



TOMOCERUS FLAVESCENS TuUberg. 



Plate 40, figs. 1, 2. 



Macrotorm flavescens Tullberg, 1871; 1872.— Reuter, 1876.— Uzel, 1890. 

 Tomocerus Jlavescens Schott, 1894.— Dalla Torre, 1895. — -Schafper, 1896. — ■ 



Poppe and Schaffer, 1897. — Lie-Pettersen, 1897; 1898. — Scherbakov, 



1898a, 18986.— Carl, 1899; 1901.— Skorikow, 1900.— Krausbauer, 1901. 

 Tomocerus niger Reuter, 1895. — Carpenter and Evans, 1899.— Schaffer, 



1900.— BoRNER, 1901.— FoLSOM, 1902.— AxELSON, 1904.— Banta, 1907. 

 Tomocerus plumbeus Packard (part), 1873. — Agren, 1903. — (Axelson) Linna- 



NiEMi, 1905, 1906, 1907.— Wahlgren, 1906. 

 Pogonognathus plumbeus Borner, 1909. — (Axelson) Linnaniemi, 1912. 



Description. — The typical T. jlavescens as known in Europe has the 

 following distinguishing characters, as appears from the pubUshed 

 descriptions and figures and from the specimens that I have received: 



Body color yellow; either pure yellow or with a varying amount of 

 purplish or grajdsh pigmentation, especially on the anterior border 

 of the mesonotum, on the coxfe, tibise, distal portions of the femora, 

 and the first two antennal segments; the last two being purplish. 

 Antennae shorter than the body. Unguis (pi. 40, fig. 1) usually bi- 

 dentate,, occasionally tridentate. Unguiculus lanceolate, Tvith one 

 tooth or with none. Dental spines (pi. 40, fig. 2) 6 to 8; large spines 

 three; one proximal and two distal; the intermediate spines be- 

 coming successively smaller toward the base of the dens. Near each 

 large proximal spine is a transparent lanceolate lamella. Length 

 5 mm., occasionally 6 mm. 



Variation. — There is great variation in the body color. TuUberg's 

 original description reads, "ground-color yellowish gray or pure yel- 

 low," and Brook refers to the color variation as follows: "The 

 majority have had yellow as the basis of the ground-color, sometimes 

 with brown patches and sometimes with the yeUow fading away into 

 a leaden color almost like that of the scales." 



Tullberg gave the first recognizable description of tliis species. 

 His description, giving the teeth of the unguis as two and the dental 

 spines as seven or eight, has been supplemented by Agren ('03), who 

 mentions the occurrence of three teeth on the unguis and gives as the 

 formula for the dental spines 1-3/3-5, 2. In eight European speci- 

 mens sent to me by Doctor Schaff'er the teeth of the unguis number 

 either two or three, and the dental formula is 1/4-5, 2. 



Some of my specimens from various parts of the United States 

 agree exactly with European descriptions and specimens of the spe- 

 cies. In this country, however, three teeth on the unguis are the 

 rule in large specimens, small individuals having usually two, and in 

 large specimens the number of dental spines ranges from 9 to 12, 

 inclusive; thus specimens 4.5 to 5 mm. in length have the formula 

 1/8, 2 or 1/9, 2. 



