SEVENTEENTH ANNUAL EEPOET. 



401 



linear, resting on the back of the external apophysis, terminal tooth pointed out- 

 ward; external apophysis elongate, nearly parallel to digit, recurved at its base and 

 its apex, in two similar nearly parallel hooks. Palpi free, ' cylindrical, the four 

 articles rather similar. Legs slightly unequal, pair II being shortest, pair IV longest; 

 femur and tibia (except of pair I) form pseudo-articulations at a distance from proxi- 

 mal end about equal to their diameter; coxse contiguous or subcontiguous; tarsi of 

 adult without pulvillum. Dorsal and ventral plates (shields, scutum, etc.) absent. 

 Stigmata between III and- IV pairs of legs, lateral of coxa3. Genital pore median, 

 at height of II intercoxal interval; male pore narrow, semilunar, nearly as long as 

 broad; vulva an elongate slit, with parallel labia and nearly as broad as capitulum. 

 Sexual dimorphism not very pronounced. 

 Type genus. — Argas Latreille, 1796. 



There has been considerable difference of opinion as to whether this 

 group is more closely related to Dermanysstis and Gamams or to 

 Ixodes. At present the consensus of opinion places it nearer Ixodes. 

 The majority of recent authors consider the forms in question as rep- 

 resenting a subfamily, but it appears to us that the presence or 

 absence of the scutum is such an important character that family rank 

 is not too low. The position of the head as inferior in adults, the 

 position of the stigmata, and absence of the pulvillum from the 

 tarsi of the adult, are also important characters which distinguish the 

 Argasidse from the Ixodidse. 



Genus Argas ^ Latreille, 1796. 



Geneeic diagnosis. — Argasidx: Body flattened, with oval or orbicular contour; 

 posterior end more bluntly rounded than anterior; broadest portion posterior of 

 coxae IV. Hood projection above capitulum spread out on the level of the dorsal 

 surface. Lateral margins thin or a little thickened. Tegument not mammillated, 

 but slightly roughened by irregular zigzag wrinkles or folds, which are absent only 

 at certain points occupied by nearly circular pits; the latter are more or less numerous 



^Synonymy and Bibliography. 



1796: Argas Latreille, 1796, p. 178. — Idem, 1804, p. 53; type, Amrus reflexus. — Idem, 

 1806, pp. 155, 156.— Idem, 1829, pp. 288, 289.— Idem, 1835, p. 512.— Leach, 1815, 

 p. 397.— Eisso, 1826, p. 182.— Heyden, 1826, p. 612.— Audouin, 1832, pp. 413, 

 414.— SuNDEVALL (1833).— DuGES, 1834a, pp. 14, 19.— Idem, 1834c, pp. 31, 32.— 

 Gervais, 1844, pp. 229-233.— Idem, 1847, p. 351.— Koch, 1844, p. 219.— Idem, 

 1847, p. 12. — Gervais & van Beneden, 1859, pp. 455, 459, 460. — Gerstaecker, 

 1860, p. 464.— Idem, 1863, p. 344.— FtiRSTENBERG, 1861, p. 208.— Moquin- 

 Tandon, 1861, pp. 304, 305.— Verrill, 1870, p. 116.— Megnin, 1876, pp. 288, 

 295.— Idem, 1880, pp. 133-136, 320-322.— Con il, 1877, pp. 27, 28, 29.— Idem, 

 1878, p. 101.— Murray, 1877, pp. 180-182.— Canestrini & Fanzago, 1877, pp. 

 193, 194.— Berlese, 1885, p. 131.— Ludwig, 1886, p. 612.— Railliet, 1886, pp. 

 499-502.— Idem, 1893, pp. 715-718.— Neumann, 1888, pp. 89, 95, 96.— Idem, 

 1892a, pp. 92, 100, 101.— Idem, 1892b, pp. 96, 104, 105.— Idem, 1896, pp. 3-25.— 

 Blanchard, 1890, pp. 329-339.— Canestrini, 1890, pp. 530, 531-536.— Idem, 

 1892, p. 582.— Trouessart, 1891, pp. 290, 291, 292, 293, 294, 295, 300, 305.— Idem, 

 1892, pp. 35, 47.— Efisio, 1892, p. 257.— Marx, 1892, pp. 233, 234.— Osborn, 

 1896, pp. 255, 256.— Morgan, 1899, p. 137.— Ward, 1900a, pp. 196-198.— Idem, 

 1900b, p. 437.— Salmon & Stiles, 1901, pp. 401-406. [Not to be confused 

 with Argas Scoul., 1835, crustacean; Arges Hann., 1835, crustacean; Arges 

 Goldf., 1839, crustacean; ArgesY al., 1840, fish; Argus Boh., 1761, mollusk; 



