254 AMERICAN PARASITIC COPEPODA. 
Fie. 15.—Mouth-parts ; ma, maxilla; mxp, maxillipede ; st, maxillipedary 
sternum ; mm, muscles ; ch, points to the chitinous bar which 
runs from the socket of maxillipede to the socket of the maxilla. 
Fie. 16.—1st pair of natatory limbs ; s, the sternum ; a, the socket ; b, the 
basal joint; vi, ramus internus ; re, ramus externus. 
Fie. 17.—Genital segment and rest of abdomen from below; go, genital 
orifice ; ch, chitinous rods. 
Fic. 18.—Attachment of egg-sac to genital aperature, showing the disposition 
of the chitinous rods. 
PLATE II. 
ILLUSTRATING ACHTHERES MICROPTERI. 
Fic. 1.—Head of female from ventral surface ; lettering as above. 
Fia. 2.—Mandible of female. 
Fic. 3.—Empty spermatophore detached from female. 
Fic. 4.—Internal maxillipedes. 
Fic. 5.—End of abdomen, female, to show the canals for impregnation with 
their orifices, v 0, to which the brown capsules are often found 
attached. 
Fie. 6.—Outline of male from side ; m, the mouth ; p, the cylindrical process 
from the external maxillipedes. 
Fic. 7.—The two pairs of antennae of the male from the inner aspect ; ch, 
the chitinous supporting plates. 
Fie. §.—First pair of maxillipedes. 
Fie. 9.—Right 2nd maxillipedes from below ; p1, the cylindrical process. 
Fic. 10.—Abdomen of male from below ; the preparation is slightly oblique ; 
J, the furcal appendages ; g/, the glandular heaps in these; a, 
the arms ; in, the intestine ; m m, muscles of the abdominal wall 
broken ; ¢, the testis ; vd', 1st, vd?, 2nd portion of vas deferens. 
Fic. 11.—Spermatophores dissected out, the ripe one ruptured below the 
neck-like constriction which joins it to the developing spermato- 
phore; the globular cement mass is emerging, behind it are the 
rod-like spermatozoa ; the discharging corpuscles still line the 
wall of the spermatophore ; spp, the spermatophoral pouch ; gl, 
the glands which secrete the cement which fixes the spermato- 
phore in the first place to the abdomen of the female. 
