E. A. Aiidreics — Anatomy of the Spider Crab. 121 



r, ridge forming the lower edge of the supero-lateral ossicle ; s, imperfect ossicle on 

 the side of the anterior pyloric pouch ; si, supero-lateral ossicle ; ta, transverse meso- 

 pyloric ossicle ; ujj, up\ up", uropyloric ossicles ; x, projecting spatulate process ; 2, 

 small plate forming part of the rim at the lower edge of the pylorus. 



Fig. 18. — Dorsal view of the cuticular lining of the stomach; enlarged about two 

 diameters : c, cardiac ossicle ; I, lateral tooth of the urocardiac ossicle ; pt, pterocar- 

 diac ossicle ; t, teeth of the supero-lateral cardiac ossicle; other letters as in fig. 17. 



Pig. 19. — Right side of the alimentary canal; about natural size: «, one of the 

 two anterior muscles of the oesophagus ; ag, antero-gastric muscle ; an, anus ; h, one 

 of the two posterior muscles of the oesophagus ; c, cardiac region ; h, opening 

 of the left hepatic duct ; i, anterior part of the intestine ; i', posterior part hned 

 with a chitinous cuticle ; lb, labrum ; I, I', lateral muscles of the oesophagus ; 

 m, m', m", lateral extrinsic muscles; n, n', n", n'", lateral intrinsic muscles; 0, 0', 

 lateral intrinsic muscles of the pylorus ; p, pylorus ; 5, muscular ring surrounding the 

 valvular opening between the two portions of the intestine ; u, left anterior csecal 

 appendage ; w', posterior unpaired csecal appendage. 



Fig. 20. — Somewhat diagrammatic view of the nervous system of a male ; about 

 natural size. The right side has been cut away to a lower level than the left 

 and the nerves to the mouth parts, three of which are cut on the right, are farther 

 apart than in nature : a, anterior extrinsic muscles of the oesophagus ; an, nervous 

 cords passing into the abdomen ; c, commissure ; eg, cephalic ganglion ; dn, cephalic 

 nerve supplying the dermis ; e, orbit ; era, endostomal plate ; g, swollen portion of 

 commissure; gg, green gland; i, intestine; fc, nervous cord connecting the commis- 

 sures ; V, superior lateral extrinsic muscle of the cesophagus ; m, altachmemt of the 

 large lateral cardiac muscle ; mo, motor nerves of the eye-stalk ; n, united pneumo- 

 gastric nerves arising from g ; ce,, oesophagus ; r", sternal artery ; r'", inferior 

 abdominal artery ; re, recurrent cutaneous nerves ; vd, terminal portion of the vas 

 deferens; I-ll, branches of the sternal artery supplying the appendages of the 

 cephalothorax, with I'-ll', their upper branches, supplying the muscles of the 

 apodemal cells ; i-xiv, nerves supplying the fourteen pairs of appendages of the 

 cephalothorax. 



