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ig. 9. 
ON THE MUSCULAR AND ENDOSKELETAL SYSTEMS OF LIMULUS. 
last pair of branchio-thoracic muscles are seen, rising from the front edge of 
the metasomatic sternite (p.ab.s¢). 
Ventral view of the plastron or thoracic entochondrite, after all muscles have 
been removed. 
View of the dorsal face of the plastron, with the various plastro-tergal and 
plastro-entapophysial muscles &c. 
Dorsal view of the plastron, the left edge cut away to show the plastro-coxal 
muscles (82-44) entering the entocoxites. (The dorsal process (d.c.en) is 
represented as rather too rounded at the top.) 
Ventral view of the plastron, with the various plastro-coxal muscles attached on 
the observer's right. 
An entocoxite, being the inner articular surface of a prosomatic appendage. 
It is made up of an anterior (a) and a posterior (pb) border, and superiorly 
of a knob (#) to which the tergo-coxal (25) is attached, and of a coxal pivot 
(cp), by which the appendage is articulated with the sternal plate of the 
carapace. 
A mesosomatic entochondrite seen from below. 
A mesosomatic entochondrite from in front (represented with its ventral face 
upwards). 
ig. 10. A transverse section across the mesosoma (from C to D, Pl. LX XII.), showing 
the thick wall, with a canal within it. The sternal region rises to meet 
the tergal, and leaves but a narrow membranous area for the attachment of 
the appendage (a), which has been removed. 
ig. 11. A transverse section across the metasoma (from A to B, Pl. LXXII.), showing 
complete chitinous floor (p.qd.st). 
