A Comparative Study of the Chromosoines etc. 
293 
Explanation of Plates. 
All drawings of Plates XIX — XXI were niade with the aid of a cainera lucida. 
In all cases the projection distance was 400 mm and the tube length 160 mm. The 
combination used in aU the figures, wnth the exception of Figure 29, Plate XIX, 
was a Zeiss 2 mm apochromatic objective and a No. 18 compensating ocular, giving 
a magnification of 3300 diameters. The figures were subsequently reduced one third. 
Figures 7 — 13 (Plate XVIII) are photomicrographs of preparations, and were made 
with the Edinger apparatus of Leitz. 
Abbreviations. 
cam.tr m. = terminal chamber; 
cl.apx. = apical cell; 
cys.deg. = degenerating cyst; 
fil.trm. = terminal filament; 
gl.muc. = mucilaginous gland; 
M. = macrochromosome ; 
nll.chr. = chromatic nucleolus; 
oal. = ovariole; 
o’(P. = o\aduct; 
ov. = ovary; 
np'tlie. = spermatheca; 
tu. = tubule; 
te. = testis; 
ut. = Uterus; 
va.df. = vas deferens; 
vsl.sem. = vesicula seminahs; 
X = a;-chromosome or a:-component of paired allosomes ; 
xij — aUosome pair of Enchenopa hinotata ; 
y = ü/-component of allosomo pair, Enchenopa binotato. 
Plate XVin. 
Fig. 1. Enchenopa binotuta, characteristic form. Female above, male below. x 2,1. 
Fig. 2. Enchenopa curvata, characteristic form. Female above, male below. x 2,1. 
Fig. 3. Nymph of E. binotata previous to final moult. x 1.6. 
Fig. 4. Nymph of E. curvata previous to final mo>ilt. x 1.6. 
Fig. 5. E. binotata. Types to show Variation of this species. Specimens from 
\ndely separated localities of the United States. Nine females above, six males below. 
X 1.6. 
Fig. 6. E. curvata. Types to show Variation of this species. Specimens from 
a single field of the same locality. Eleven females above, eight males below. x 1.6. 
Fig. 7. Testis of E. curvata. x 25. 
Fig. 8. Longitudinal section of distal half of a tubule (testis of E. binotata), the 
section passing through apical cell. Degenerating cyst is seen below the apical cell, x 240. 
Fig. 9. Immature ovary of E. binotata. x 25. 
