334 



ME. W. B. S. BENHAM ON THE MUSCULAR 



88. Mid-ventral entapophysio-pygal. 



89. Extcrno-ventral entapophysio-pygal. 



90. Interno-ventral entapophysio-pygal. 



91. Externo-dorsal entapophysio-pygal. 



92. Mid dorsal entapophysio-pygal. 



93. Interno-dorsal entapophysio-pygal. 



94. Internal sternal slip from 7 (a tergo-pygal). 



95. External sternal slip from 7 (a tergo-pygal). 



96. Internal sternal slip from 8 (a tergo pygal). 



97. External sternal slip from 8 (a tergo-pygal). 



103. A slip from 73 to the third entapophysis. 



104. A slip, partly from 2 and partly from 73 to 



fourth entapophysis. 



105. A slip from 2 to fifth entapophysis. 



106. A slip from 2 to sixth entapophysis. 



107. Terminal portion of 2 (the ventral entapophysio- 



plastral). 



112. Muselo from a sclerite (p) on mesosomatic 



appendage to the outer lobe of the same. 



113. A slip from 20 to sclerite (a) on the meso- 



somatic appendage. 



114. A muscle from sclerite (p) on mesosomatic 



appendage to tho inner lobe of the same. 



115. A slip from 48 to sclerite (p) on the meso- 



somatic appendage. 



i.-vi. Prosomatic appendages. 



vii.-xii. Mesosomatic appendages. 



vn a. Immovable spine belonging to the first meso- 

 somatic segment. 



vm a.-xm «. Movable spines corresponding to the 

 last five segments of the mesosoma and the 

 first of the metasoma. 



PLATE LXXII. 



The floor of the animal (natural size) after removal of muscles and viscera. It 

 shows the raised subfrontal area (sfa), the great arching of the chitinous 

 floor at the sides (cen), whilst along the line of attachment of the appendage 

 there is a nearly vertical dip ; the walls of this hollow being formed by 

 the entocoxites and the intervening membrane. In the middle of the 

 prosoma or thorax is seen the cut oesophagus («), in front of this the 

 camerostome (cam), and behind it the " promesosternite " ; behind these 

 again are seen a pair of cavities leading into the chilaria (metasternite). 

 The transverse hollows (vii-xii) in the mesosomatic floor are the entrances 

 to the spaces between the plates of the mesosomatic appendages; the 

 hollow tendons (ts) of the branchio-thoracic muscles are seen. On the 

 post-abdominal sternal region (p.ab.st) are seen the areas of attachment of 

 some of the pygal muscles. Behind this is the cut rectum, and then the 

 post-anal spine or " pyge." On the left the wall of the mesosoma has been 

 cut away to show the canal (ca), which runs forwards to the front part of the 

 mesosoma, and holds blood-vessels and nerves. 



PLATE LXXIIL 

 The carapace and heart have been removed, and the alimentary canal. Fig. 1 is a 

 more superficial dissection than fig. 2. 



Fig. 1. On the right side the dissection is more superficial than on the left: the tergo- 

 coxals (24, 25) are seen attached to the " knob " of the entocoxites. That 

 of the first appendage (24) is seen nearer the middle line than the rest. 



