X 



ANATOMY- -HAIJITS 267 



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- 

 steruite. 



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 nmsrles. Botli 

 branches of the haemal nerve are represented extending into the telson (2f>). 



The intestinal nerves are shown arising from the haemal nerves and filtering 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 brandies 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 ha. 

 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 int. r- 

 tergal muscles and the epidermis in the median line, but the connection-: with the 

 eardiac 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 lias 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 m< 

 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 la.-t 

 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 neuron, 

 from the eighth to the fourteenth, either through the cardiac nerves or the hai 

 nerves, and innervates the branchio-thoracic muscles, extending with these lar into 

 tin- cephalothorax. 



1, Mouth ; '2, rostral nerve in labnuu ; 3, anterior commis>niv ; I, chelicera : 5, 

 olfactory nerves ; b', stomodaeal nerve ; 7, lateral eye-nerve ; 8, 2nd haemal i 

 9, lateral nerve ; 10, median eye-nerve; 11, median eye ; 1 '_', proventriculus | I-"., 

 frontal artery ; 11. aortic arch ; 15, anterior hepatic duct of li\ ei ; 1 h, nearl : 17, 2nd 

 Hum : IS, 7th and Sth segmental cardiac nerves ; 111, one of the lateral arterfi , 

 20, pericardial nerve; 21, lateral cardiac nerve; 22, median cardiac nerve; 23, 



intestine; 24, levator ani muscle; 2.">, telson ; 26, anus ; 27, sphincter ani 



28, last branehial appendage ; 29, 1 f,th haemal nerve; -". lateral sympathetic QI 

 I!], Mh abdominal cndorhondi ite ; .'!2, genital opereiilnm : .".:'.. eliilariiini : 



fiidosternit'' : :'..">, ventral nerve cord; :!6, 6th haemal nerve; '\7 , Olig f '>th 



neural ner\ e. 



Li inn! a* feeds j.art ly nn bivalves, hut mainly <>n worms, especi- 

 ally Nereids, which it catches with its ehelate limbs as it lmrni\\> 

 through the sand. The food is held immediately under tin- mmith 



by the ehelieerae, aided at times by the sure linu appendagi 



it is thus brought within range of the gnathobases <>f tin- 



