x ANATOMY—HABITS 207 
off just beyond the point where it fuses with the second haemal nerve (8). The 
stomodaeal nerve (6) ramifies over the oesophagus and proventriculus. 
The second haemal nerve (8) passes to the anterior extremity of the carapace ; 
its haemal branch is cut off opposite the proventriculus. An intestinal branch 
arises from near its base and disappears behind the anterior cornu of the endo- 
sternite. 
The next three haemal nerves (36) are cut off close to the brain, and the 
following nine haemal nerves are cut off beyond the cardiac branches. The fifteenth 
haemal nerve (29) is cut off beyond its branch to the telson muscles. Both 
branches of the haemal nerve are represented extending into the telson (25). 
The intestinal nerves are shown arising from the haemal nerves and entering the 
intestine. Those from the sixth and seventh neuromeres pass through foramina in 
the endosternite, and communicate with a plexus in the longitudinal abdominal 
muscles before entering the intestine. The eighth passes just posterior to the endo- 
sternite and joins the same plexus. Those from the first four branchial neuromeres 
arise very near the abdominal ganglia, and are double in their origins, the anterior 
branches joining the above-mentioned plexus, and the posterior branches entering 
the intestine. The fifteenth extends far back towards the rectum and anastomoses 
with the sixteenth, which arises from the caudal branch of the sixteenth haemal 
nerve, and innervates the rectum and anal muscles. 
The segmental cardiac nerves (18) arise from the haemal nerves of the sixth to 
the thirteenth neuromeres respectively. The most anterior one passes to the inter- 
tergal muscles and the epidermis in the median line, but the connections with the 
cardiac plexus have not been made out. The next two (18) fuse to form a large 
nerve, which passes to the inter-tergal muscles and epidermis, but has not been 
observed to connect directly with the cardiac plexus. It, however, sends posteriorly 
a branch, the pericardial nerve (20), which in turn gives a branch to each of the 
cardiac nerves of the branchial neuromeres, and then continues onward to the 
posterior margin of the abdomen. ‘This nerve lies in the epidermis. The median 
and lateral cardiac nerves (22 and 21) are seen upon the walls of the heart. The 
five cardiac nerves from the branchial neuromeres pass, in the epidermis, to the 
median line, and dip down to the median nerve (22) of the heart opposite the last 
five pairs of ostia (17). They communicate with the pericardial nerve (20) and also 
with the lateral sympathetic nerve (30). 
Two post-cardiac nerves pass from the first and second post-branchial nerves to 
the epidermis posterior to the heart. 
The last cardiac nerve and the two post-cardiac nerves give off branches which 
anastomose with each other and innervate the extensors of the telson. 
The lateral sympathetic nerve (30) receives branches from all the neuromeres 
from the eighth to the fourteenth, either through the cardiac nerves or the haemal 
nerves, and innervates the branchio-thoracic muscles, extending with these far into 
the cephalothorax. 
1, Mouth ; 2, rostral nerve in labrum ; 3, anterior commissure ; 4, chelicera ; 5, 
olfactory nerves ; 6, stomodaeal nerve ; 7, lateral eye-nerve ; 8, 2nd haemal nerve ; 
9, lateral nerve ; 10, median eye-nerve ; 11, median eye ; 12, proventriculus ; 13, 
frontal artery ; 14, aortic arch ; 15, anterior hepatic duct of liver ; 16, heart ; 17, 2nd 
ostium ; 18, 7th and 8th segmental cardiac nerves ; 19, one of the lateral arteries ; 
20, pericardial nerve; 21, lateral cardiac nerve; 22, median cardiac nerve ; 23, 
intestine ; 24, levator ani muscle ; 25, telson; 26, anus ; 27, sphincter ani muscle ; 
28, last branchial appendage ; 29, 15th haemal nerve; 30, lateral sympathetic nerve ; 
31, 8th abdominal endochondrite ; 32, genital operculum; 33, chilarium; 34, 
endosternite ; 35, ventral nerve cord; 36, 6th haemal nerve; 37, origin of 6th 
neural nerve. 
Limulus feeds partly on bivalves, but mainly on worms, especi- 
ally Nereids, which it catches with its chelate limbs as it burrows 
through the sand. The food is held immediately under the mouth 
by the chelicerae, aided at times by the succeeding appendages ; 
it is thus brought within range of the gnathobases of the 
