300 
W. M. Wheeler 
s]ß mature spermatozoa. 
spc spermatocytes dividing-. 
spg spermatogonia. 
spg.p spermatogonia dividing. 
st seta. 
st.c gland-cell which secretes 
str striated zone. 
s.v ventral body-wall. 
the seta. y yellow concretions. 
ts testes. 
ut »Uterus«. 
v.s vesiculae seminales. 
ver small wart-like projections of the 
z thickening in the mid Sventrai line of 
dorsal integument. 
M. platypus. 
Plate 10. 
Myzostoma cirriferum Figs. 1 — 17; 31. circinatum Fig. 18; M. glabrum Fig. 19 — 23. 
Fig. 1. Median portion of a horizontal section through the region of the ovaries of 
a M.cirriferumì.l^ mm long. Gundlach obj. l^/ginch; Zeissoc. 3= lOOx. 
Fig. 2. Median portion of a horizontal section through the region of the ovaries 
of a M. cirriferum 1 mm long. Gundlach obj. 1 2/3 inch ; Zeiss oc. 3 =100 x. 
Fig. 3. Transverse section through the middle of the body of a M. cirriferum 
0.6 mm long. Gundlach obj. 1^/3 inch; Zeiss oc. 3 = 100 x. 
Fig. 4. Transverse section through the anterior pair of ovaries of a M. cirri- 
ferum 1.75 mm long. Gundlach obj. l^/s inch; Zeiss oc. 3 = 100 x. 
Fig. 5. Median sagittal section of a M. cirriferum 1.75 mm long. Gundlach 
obj. 12/3 inch; Zeiss oc. 3 = 100 x. 
Fig. 6 a — c. Stages in the early growth of the ovum of M. cirriferum (corrosive 
subì, hardening). Zeiss hom. immer. V12; oc. 3 = 730 x. 
Fig. 7. Five young ova of the same species, hardened in picroacetic acid. 
Zeiss hom. immers. V12; oc. 3 = 730 x. 
Fig. 8. A young ovum of the same species. Picroacetic acid. Zeiss hom. 
immers. V12; oc. 3 = 730 x. 
Fig. 9. Somewhat older ovum of M. cirriferum. Picroacetic acid. Zeiss hom. 
immers. V12; oc. 3 = 730 x. 
Fig. 10. Ovum in about the same stage as Fig. 9. Picroacetic acid. Zeiss hom. 
immers. V12; oc. 3 = 730 x. 
Fig. 11. Older ovum still showing the enlarged con tours of the accessory nuclei. 
Picroacetic acid. Zeiss hom. immers. V12; oc. 3 = 730 x. 
Fig. 12. Young ovum with two nucleoli. Picroacetic acid. Zeiss hom. immers. 
1/12; oc. 3 = 730 X. 
Fig. 13. Older ovum with pieces of a Spermatozoon in its cytoplasm. Picro- 
acetic acid. Zeiss hom. immers. V12; oc. 3 = 730 x. 
Fig. 14. Older ovum with two nucleoli. Picroacetic acid. Zeiss hom. immers. 
I/12; oc. 3 = 730 X. 
Fig. 15. Mature ovum. Picroacetic acid. Zeiss hom. immers. V12; oc. 3 = 730 x. 
Fig. 16. Transverse section of a M. cirriferum 0.35 mm long. Zeiss hom. immers. 
V12; oc. 2 = 530 X. 
Fig. 17. Next section to the one represented in Fig. 16. Zeiss hom. immers. 
1/12; oc. 2 = 530 X. 
Fig. 18. Myzostoiua circinatum n. sp. seen from the ventral surface. 10 X. 
Fig. 19. Transverse section through the region of the ovaries of a M. glabrum 
1 mm long and attached to the disc of the Atitedon. Gundlach obj. 
12/3 inch; Zeiss oc. 3 = 100 x. 
