SEVENTEENTH ANNUAL REPORT. 



463 



The Castor-Bean Tick {Ixodes ricinus).^ 



(Figures 222-227.) 



Specific diagnosis. — Ixodes: Male. — Body oval, with broader posterior border, 

 rounded, entire; 2.5 mm. long (including capitulum), 1.5 mm. broad; deep red brown 

 on all parts. Scutum convex, coveiing entire dorsal surface, except a clearer narrow 

 marginal swelling; punctations very fine and abundant; cervical grooves very super- 

 ficial. Genital orifice broad, on plane of coxse III. Pregenital shield a third longer 

 than broad, narrower and rounded 

 or sinuous in front, with convex 

 sides. Anal shield a little longer 

 than broad, ogival, sides straight 

 and divergent. Anus same as in 

 female. Very apparent hairs scat- 

 tered on entire surface; those of 

 the epimeral shields having their 

 insertions reinforced by puncti- 

 form thickenings. Capitulum 

 500 jj. long, its base twice as broad 

 as long and of trapeze form, open 

 in front on the dorsal surface, a 

 little longer than broad on the 

 ventral surface, which has the 

 same form as in the female. Man- 

 dibles 750 /uL long, digit 180 jj- long; 

 the sheath of the stem simply cor- 

 rugated transversely; internal 

 apophysis of the digit applied 

 against the dorsal face of the an- 

 terior half; with three points, an 

 anterior terminal, small, one which follows immediately, larger, and a basal, feeble; 

 the broad base not extending beyond the middle of the length of the digit; external 

 apophysis with seven or eight teeth, the anterior progressively larger and forming a 

 comb or crest, the posterior basal very strong. Hypostome bearing on each side a 

 marginal series of six to eight teeth, increasing in strength from before backward; 



Fig. 222. — Male Ixodes ricinus. Ventral view. After Neu- 

 mann, from Railliet, 1893, p. 707, fig. 481. 



^ Synonymy and Bibliography. 



1758: Acarus reduvius Linn^us, 1758, p. 615, and 1760, p. 615 [in part only; chiefly 

 Melophagus ovinus']; not 1761, p. 47, > [= Acarus ovinus, 1746, p. 346; Reduvius, 

 or sheep's tick Charleton, 1668, p. 49; Pedimdus ovinus Ray, 1710, p. 9; 

 Schaf-Laus Fritsch, 1724, pp. 40, 41, Tab. xviii, figs. 1, 2.].— De Geer, 1778- 

 pp. 101-106.— Fabrici us, 1794, p. 425.— Jordens, 1801, pp. 194, 195, Tab. vii, 

 figs. 7-9. [Given as syn. of Ixodes reduvius by Latreille, 1804, p. 51. — 

 Gervais, 1844, p. 237. — Canestrini & Fanzago, 1877, p. 180. — Railliet, 

 1893, p. 706.— Neumann, 1899, p. 112.] [See also Duges, 1834c, p. 33.— 

 Latreille, 1829, p. 288.] [Given as syn. of Ixodes ricinus by Moquin-Tan- 

 don, 1861, p. 302, and of Ixodes reticulatus, p. 303.] 



1758: Acarus ridnus Linn^us, 1758, p. 615; 1760, p. 615; 1761, pp. 479, 480 [Ricinus 

 Charleton, 1668, pp. 49, 50; Ricinus octopodus, the tick of Ray, 1710, p. 10; 

 Hund-Laus, Zsecken, Tsecken of Fritsch, 1724, p. 41, Tab. xix]. — Fabricius, 

 1794, p. 425. — DuNGLisoN, 1900, p. 7. [Given as syn. of Ixodes ricinus by 

 Latreille, 1804, p. 51.— Idem, 1829, p. 288.— Fabricius, 1805, p. 351.— 

 Leach, 1815, p. 397.— Gervais, 1844, p. 236.— Moquin-Tandon, 1861, p. 

 302.— Canestrini & Fanzago, 1877, p. 180.— Blanchard, 1890, p. 324.] 



