AND ENDOSKELETAL SYSTEMS OF SCOEPIO. 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 LXXVIII. 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) is a 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 exterior first dorso-coxal muscle (109) is attached to the carapace near the 



3g2 



