96 



ZOOLOGY. 



ing the food, which the horseshoe obtains by burrowing in the mud 

 or sand. The mouth is situated between the second pair; the first 

 pair of legs are smaller than the others. All end in two simple 



Fig. 120.— Actual section through the head of Limulus, showing the second pair 

 of appendages and their relations to the shell or carapace, ht, heart; liv, 

 liver; end, appendage homologous with the endopodite of Decapoda. 



Fig. 121.— Section through the abdomen of Limulus. c, carapace; ht, heart; int, 

 intestine; ng, ganglia (lettering being the same as in Fig. 123 1 ); en, axial, 

 jointed endopodite; ex. exital or respiratory portion bearing the gill-lamellas ; 

 the outer division (ex) homologous with the exoijodal portion of the Phyllo- 

 pod and Phyllocaridan leg. 



(laws (Fig. liO), except the sixth pair, which are armed with several 

 spatulate appendages serving to prop the creature as it burrows into 

 the mud. Appended to the abdomen are six pairs of broad swim- 

 ming feet (Fig. 121, ex), of which all but the first pair bear on th» 



