1 66 PATTEN AND REDENBAUGH. [Vol. XVI. 



the large blood vessel which accompanies the last haemal nerve 

 into the telson. In alcoholic specimens white blood clots are 

 often found in the forks of the arteries, and these might easily 

 be mistaken for ganglia in a gross dissection. Such a clot is 

 often found at the spot designated by Milne-Edwards, but 

 microscopic examination reveals no ganglion cells. 



There are no post-cardiac branches in the terminal neuro- 

 mere. 



3. Sympathetic Systems. 

 a. Lateral SympatJietic. 



Milne-Edwards in 1873 described the lateral sympathetic as 

 a lateral longitudinal nerve parallel to the ventral cord. Refer- 

 ring to the abdominal haemal nerves he says : " Chacun d'eux 

 envoie un filet qui se dirige en avant, et va se reunir, ou plutot 

 concourt a former un nerf lateral longitudinal. Celui-ci " (the 

 lateral sympathetic nerve) " s'etend parallelement a la chaine 

 ganglionnaire, un peu en dehors de la veine collectrice et entre 

 les muscles abdominal-oblique et branchio-thoracique ; il se pro- 

 longe en avant jusqu'au thorax, et en arriere il pr^sente un 

 petit renflement ganglionnaire ; dans son parcour il fournit des 

 filets aux muscles voisins. Ce nerf latero-abdominal, dont I'ex- 

 istence n'a jusqu'a present ete signalee que chez les Limulus, 

 rappelle par sa position le grand sympathique des animaux 

 superieurs ; mais son role physiologique est tout a fait different, 

 puisque au lieu de se distribuer aux organes de la vie de nutri- 

 tion, il se rend aux organes de la vie de relation." 



I have found that the lateral sympathetic nerve (Text-figs. 9, 

 15, 16, and 18 ; Pis. VI, VIII, and IX, Figs, i, 3, and 6, l.s.n), 

 which has already been partially described, lies nearly parallel 

 to the ventral cord, and receives a branch from each of the 

 haemal nerves, from the eighth to the fourteenth, inclusive. It 

 is in close connection with the branchio-thoracic muscles {b.i.m.), 

 and its anterior portion is formed of anastomosing branches 

 within, and forming the nerve supply of, this bundle of mus- 

 cles. It extends as far forward into the cephalothorax as do 

 the branchio-thoracic muscles. The posterior portion consists 



