TRÄGÅRDH, MORPHOLOGY AND PHYLOGENY OF PARASITID^. 23 



withoiit secondary sexual characteristics, the same applies to 

 the legs; in neither sexes tbe dorsal sbield is simple, in the 

 female and nympha of Sejus it is even divided into six 

 shields. 



The latter genus also possesses primitive features in the 

 structure of the ventral shields (comp. above). The male 

 genital aperture is, in Zercon, placed exactly in the same 

 place as in the female, e. g. between coxae III, but bas in 

 Sejus moved further forwards. 



Finally, the Rhodacarinoe, ha ve a very primitive feature, 

 to judge from Oudemans' description and figures, that in 

 the female the genital aperture is situated behind coxse IV. 



In other respects, however, they are modified and, on the 

 whole, we may conclude that of the Parasitidce, as yet known, 

 the genera Zercon and Sejus are the most primitive ones 

 and of these tvvo Sejiis is the one who bas the greatest num- 

 ber of primitive characteristics. 



Bibliogrraphy. 



1. Beelese, a., Acari, Myriapoda et Scorpioiies hucusque in Italia 



reperta. Paclua 1882 — 94. Ordo Mesostigmata. 



2. — — ■ Monographia del Genere y>G-amasus» Latr. — Redia Vol. 



III. fasc. 1. p. 65—304. pls. 2—19. 23 textfigs. Floreiiz 

 1906. 



3. Lista di nuove speeie e nuovi generi di Acari. — Redia. 



Vol. YL fasc. 2. p. 241—271. Floreuz 1910. 



4. BöKNER, c, Arachnologische Studien (II und III) — Zool. Anz. 



Bd. XXV. X:o 673/674. vom 16. Juni 1902. p. 433— 466. 

 14 textfigs. 



5. Kramer, P., Ueber Gamasiden. — Arcli. f. Naturgescli. 1882. 



p. 374—434. pls. XIX & XX. 



6. Michael, a. D., Observations on the Life-histories of Gamasina?, 



with a view to assist in more exact Classification. — Lim. 

 Soc. Journ. Zool. Yol. XV. p. 297—309. pls. XXII & XXIII. 



7. Observations upon a spccies of Gamasus supposed to be 



unrecorded. — Journ. Quekett Micr. Club. 2nd ser. Vol. II. 

 p. 260—268. pl. XVL London 1886. 



8. Oudemans, A. C, Notes on Acari. IVth series. — Tijdschr. d. 



Xed. Dierk. Vereen. (2) Dl. VIT. Afl. 3 en 4. p. 275— 

 311. pl. VIII— X. 1902. 



