356 MISS E. J. BECK ON THE MUSCULAR 



The muscles 79, 81, & 83 run between the epimeron and the plastron, the muscle 87 

 between the epimeron and the second entochondrite, and the muscle 124 between the 

 epimeron and the pectine. 



The anterior dorso-epimeron muscle (126) is attached to the lateral portion of the 

 carapace and to the epimeron lateral to the interior margin of the second coxal sclerite. 



The median dorso-ejjimeron muscle (127) is attached to the lateral portion of the 

 carapace and to the epimeron lateral to the interior margin of the third coxal sclerite. 



The i^osterior dorso-epimeron muscle (128) is attached to the lateral portion of the 

 carapace, and to the epimeron lateral to the interior margin of the fourth coxal 

 sclerite. 



VIII. Muscles to the Pharfinx. (See Plate LXXIX. figs. 11, 12.) 



The pharynx of the Scorpion is a large dilatation of the alimentary canal closely 

 following the aperture of the mouth. This aperture is so minute that the animal lives 

 entirely on the juices of its prey, and on the hard parts finely pulverized by the action of 

 the chelicerae: these juices are drawn in at the oral aperture by the expansion and 

 contraction of the pharynx. On contracting the muscles form within the pharynx 

 a partial vacuum ; and as the aperture of the oesophagus on leaving the pharynx 

 is smaller than that of the mouth, the vacuum is more readily filled from the latter. 

 The muscles attached to the pharynx are of two kinds, the extrinsic, which dilate, 

 and the intrinsic, which contract it. It is thus rendered a powerful suctorial organ. 

 In transverse section it is shown to be very narrow, the lateral walls almost meeting ; 

 its dorsal portion is curved downwards, and forms a lateral groove, which gives it a 

 triradiate form. 



The dorsal intrinsic muscle (129) consists of three small bands of muscle which 

 are attached to the dorsal surface of the pharynx within, and to the walls on either 

 side of the groove. This muscle is so small that it is only by means of sections that 

 it is visible ; it is, of course, not repeated on either side of the animal, as it is itself in 

 the median line. 



The lateral intrinsic onuscle (ISO) runs closely by the lateral walls of the pharynx, 

 and is attached dorsally and ventrally to its walls. This muscle cannot be seen without 

 the aid of sections. 



The anterior preoral entosclerite pharyngeal muscle (98) (PI. LXXIX. fig. 12) is a 

 small muscle attached to the ventral surface of the anterior portion of the preoral 

 entosclerite. It runs down almost vertically into the groove on the dorsal surface of 

 the pharynx, to the wall of which it is attached. 



The posterior preoral entosclerite pharyngeal muscle (99) is a larger muscle 

 attached to the interior surface of the processes of the preoral entosclerite, and runs 

 almost horizontally to the lateral wall of the pharynx, to which it is attached. 



