AND ENDOSKELETAL SYSTEMS OF SCORPIO. 353 
attached to the posterior portion of the first coxal entosclerite and to the interior 
margin of the deutomerite sclerite of the first appendage. 
The third-coxal entosclerite-deutomerite muscle (102) is attached to the third coxal ento- 
sclerite and to the interior margin of the deutomerite sclerite of the third appendage. 
The fourth-coxal entosclerite-deutomerite muscle (103) is attached to the fourth 
coxal entosclerite and to the interior margin of the deutomerite sclerite of the fourth 
appendage. 
The fifth coxo-deutomerite muscle (104) is attached to the fifth coxal sclerite and to 
the interior margin of the deutomerite sclerite of the fifth appendage. 
The sixth coxo-deutomerite muscle (105) is attached to the sixth coxal sclerite and 
to the interior margin of the deutomerite sixth sclerite of the sixth appendage. 
Extrinsic Muscles.—Most of the extrinsic muscles of the appendages are attached 
to the carapace; when this is removed a compact mass of muscles is exposed, which 
is shown in Pl. LXXVIII. fig. 6. The under-surface of the carapace, with the attach- 
ments of the muscles, is represented in Pl. LX XVIII. fig. 7, and the attachments of the 
muscles to the appendages are shown in Pl. LXXIX. fig. 16. There are three series of 
extrinsic muscles to the appendages of the prosoma—those running to the deutomerite 
sclerites, the coxal sclerites, and the coxal entosclerites. 
Deutomerite Muscles.—There is one deutomerite muscle to each of the appendages 
of the prosoma, with the exception of the first, to which there are two. These muscles 
are attached extrinsically to the carapace (those running to the first and second appen- 
dages) and to the plastron (those to the third, fourth, fifth, and sixth appendages). 
The deutomerite muscles (73, 77, 80, 82) from the plastron have already been 
described under the muscles attached to the plastron; it remains to mention those 
from the carapace to the first and second appendages. 
The superior first dorso-deutomerite muscle (106) is a narrow muscle attached to the 
carapace near the median line posterior to the eyes; running forward, it is attached 
to the superior portion of the interior margin of the deutomerite sclerite of the first 
appendage. 
The inferior first dorso-deutomerite muscle (107) is a larger muscle, attached to the 
carapace more laterally. It runs forward and is attached to the inferior portion of the 
interior margin of the deutomerite sclerite of the first appendage. 
The second dorso-deutomerite muscle (108) isa thick muscle attached to the carapace 
towards its posterior portion. It runs forward to the exterior portion of the interior 
margin of the deutomerite sclerite of the second appendage, to which it is attached. 
Coxal Muscles.—The coxal muscles are attached extrinsically to the carapace, with 
the exception of three which run to the coxal sclerite of the second appendage from 
the plastron and have been mentioned above under the muscles attached to the plastron 
(72, 75, 76). 
The e«terior first dorso-coxal muscle (109) is attached to the carapace near the 
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