THE LEPTOSTRACA 



157 



placed close to the adductor muscle of the carapace at the base of 

 the maxilla. The gland in each case consists of a minute saccule 

 giving oft' a short duct, but the external openings have not been 

 detected. 



Eight pairs of glands lying at the bases of the thoracic limbs 

 are also believed to be excretory. Each consists of a thickening of 



Fig. 91. 



Pleopod of second pair of Nchalia. a.i, appendix interna ; en, endopoditc ; 

 ej;, exopodite. (After Clans.) 



the hypodermis partly surrounding the eff"erent blood-channel from 

 the epipodite. These glands alone become coloured by intra ritam 

 treatment with indigo-carmine, while the aiitennal and maxillary 

 glands excrete particles of carmine Avheu the animal has been fed 

 with that substance. 



Muscular Sijstem. — The adductor muscle (Fig. 87, ad) of the 

 carapace has two muscular heads attached to the valves and con- 



