464 



PROCEEDINOS OF THE NATIONAL MUSEUM. 



Tomocerus vulgaris Tullberg, 1876. — Reuter, 1891; 1895. — Brook, 1883. — 

 Dalla Torre, 1888.— Schott, 1894.— Schaffer, 1896; 1900a; 19006.— Poppe 

 and Schaffer, 1897. — Scherbakov, 1898.— Carpenter and Evans, 1899. — 

 Carl, 1899.— Skorikow, 1900. — Absolon, 1903. — Borner, 1901. — Kraus- 

 BAUER, 1901.— Igren, 1903.— (Axelson) Linnaniemi, 1905, 1907, 1912.— 

 Wahlgren, 19066. 



Podura vulgaris Voigts, 1902. 



Tomocerus niger Guthrie, 1903. 



Description. — General color purplish black; when denuded of 

 scales, clear yellow, dull yellow, yellowish white, dirty white, or gray. 

 Antennae two-thirds as long as the head and body in large specimens; 

 tliird and fourth segments, and often the second segment, purplish. 

 Tibiae often dusky. Unguis slender (pi. 41, fig. 9), four to six toothed; 

 unguiculus lanceolate, often minutely unidentate. Tenaculum with 

 twelve or thirteen anterior setae in large specimens. Dental spines 

 simple, usually 13 to 15, less often 12 or 16, and rarely 17 or 18, on 

 each side; formula usually 4-6, 1/2-5, 1, 2, 1; extreme formula 

 4-7, 1/2-5, 1, 1-3, 1. The large dental spines are constant in number 

 and position, and the first and third of these are out of line with the 

 rest of the series, being more lateral in position (pi. 41, fig. 10). 

 Mucrones with five to seven intermediate teeth, rarely more (pi. 41, 

 fig. 11). On the dorsum of the head are several stiff, finely feathered 

 setae. Mesonotal collar of dense setae. Maximum length, 4 mm. 



Variation. — The body-color is quite variable, as already noted. 

 Frequently the anterior border of the mesonotum is pigmented, 

 while the rest of the body is unicolorous; sometimes the meso- and 

 metanotum and the bases of the legs are mottled with pigment; or 

 the entire body may be mottled. Individuals of different sizes show 

 marked structural differences. With age, the subsegments of the 

 third antennal segment increase in number and become shorter, and 

 this segment increases in relative length, as do also the third abdomi- 

 nal segment and the dentes; furthermore, the teeth of ungues and 

 mucrones and the spines of the dentes increase in number. Some 

 of these changes in ratio and number are expressed in the following 

 table, adapted from one by Schaffer (1900, p. 275). The measure- 

 ments are from successively larger insects, beginning wath very small 

 specimens (No. 1) : 



