190 KE. A. MINCHIN. 
compact and stains deeply, so that no structure can be made 
out in it. 
The most remarkable variations can be seen in the relative 
positions of mand N. I distinguish six types!: (1) » well 
in front of N, with distinct space between (figs. 181, 182) ; 
(2) 2 just in front of N, with no space between (fig. 156) ; 
(3) 2 is at the side of, or overlapping N (fig. 175) ; (4) 1 just 
behind WV (fig. 176); (5) 1 far behind WN (fig. 160) ; and (6) x 
terminal (fig. 152). Miss HE. Y. Thomson has made some counts 
for me of the different types, which I record below : 
(1) CQ) oe) (5) 
Nov. 18. Red blood Numbers 1 30 45 | AT 320 
| (figs. 151-155, p. 243) | Percentage) 0:22) 666) 10 1O;4 Sve 
| Nov. 18. Black blood Numbers 28 145 73 WS | BG 
| (figs. 156-164, p. 243) Percentage, 3°8 2.0) eee 18°2 47°7 
Nov. 13. Proctodeum Numbers ll 55 33 62 7g: 
(figs. 165-170, p. 244)| Percentage) 3°1 159 9°56 | 17:9 En is) 
| Nov. 10. (2) Black blood | Numbers | 1138 332 168 65 17 
(figs. 188-143, p. 241) Percentage) 16°3 | 479 | 241 93 | oe 
Nov. 14. Red blood Numbers 8 158 | 108 48 42 
(figs. 171-173, p. 245)) Percentage) 2°19 | 43-4 29°67 | 13°18 | 11°53 
Nov. 14. Red-black blood | Numbers 40 | 209 863 314 207 
(figs. 174-176, p. 245)) Percentage} 2°4 12°8 52°8 19:2 12°6 
Nov. 14. Black blood Numbers | 678 8 155 20 50 
(figs. 177-182, p. 245) | Percentage) 744 0-8 17 Qe oi aero 
Oct. 10. Black blood Numbers 14 56 49 14 6 
(figs. 226a—-231, p. 233) | Percentage| 10 40°3 | 35-2 10 4°3 
Oct. 10. Red blood Numbers 95 44, 39 3 3 
(figs. 218-226, p. 232)| Percentage) 21:9 38°5 34°2 2°6 2°6 
PT UT TST tease | 
These figures show in one fly (Nov. 18th) a great preponder- 
ance of forms with n posterior to N, or even terminal, 
especially in the red blood; but in all others the forms with n 
in front of or close beside N greatly preponderate. (In these 
statistics no account is taken of the slender and the Herpe- 
1 A convenient graphic notation from these types is as follows : 
n n N N N as 
(Vs @) ys @) WlWs 4) Zs Ss © |. A type with » ter 
7 u 
D 
minal but anterior could be written | 
