LIMULUS AN ARACHNID. 539 
SCORPIO, 
Segments. 
Appendages. Sternites. Tergites. 
10 |2nd gill-book pair/Aseparatebroadtrans-|A separate band-like scle- 
sunk in pulmonary} verse sclerite with| rite. 
sacs, stigmata leading to 
pulmonary sacs. 
11 |8rd gill-book pair|Aseparate broadtrans-|A separate band-like scle- 
sunk in pulmonary| verse sclerite with) rite. 
sacs. stigmata leading to 
pulmonary sacs. 
12 |4th gill-book pair/Aseparate broad trans-/A separate band-like scle- 
sunk in pulmonary| verse sclerite with rite. 
sacs, stigmata leading to 
pulmonary sacs. 
13 |None. A separate broad trans- A separate broad band- 
) verse sclerite devoid) like sclerite. 
| of stigmata. 
4 IN one, : Ventral half of a dis-|Dorsal half of a distinct 
tinct cylindrical scle-| cylindrical sclerite. 
rite. 
15 |None. Ventral half of a dis-|Dorsal half of a distinet 
tinct cylindrical scle-| cylindrical sclerite. 
rite. 
16 |None. Ventral half of a dis-|Dorsal half of a distinct 
tinct cylindrical sele-| cylindrical sclerite. 
rite, 
17 |None. Ventral half of a dis-|Dorsal half of a distinct 
tinct cylindrical scle-| cylindrical sclerite. 
rite. 
18 |None. Ventral half of a dis-\Dorsal half of a distinct 
tinct cylindrical scle-| cylindrical sclerite. 
rite, in which is 
placed the anus. 
es te - 
Post-anal spine or sting 
(a jointed filame nt in T he- 
lyphonus). 
VOL. XXI.—NEW SER. N N 
