218 PROCEEDINGS OF THE XATIOXAL MUSEUM. vol.39. 



where it opens to the surface. The walls of this duct are composed 

 of a thick homogeneous layer, set with nuclei, and taking both the 

 red and the blue stains. 



Another pair of glands, situated in the bases of the second maxillae, 

 one on either side, may be called the maxillary glands (mxg., fig. 37). 

 Each is a single well-rounded ellipsoidal mass, nearly filling the cavity 

 of the maxilla and giving off from its inner surface at the center of 

 the ellipse a straight duct, which leads toward the distal end of the 

 basal joint, where it opens to the surface on the inner side-. 



As development proceeds the maxillipeds migrate forward, taking 

 the distal end of the convoluted duct with them, while the second 

 maxillae in the male point diagonally backward outside of the maxil- 

 lipeds. It thus comes about in the adult that the bulk of the maxilli- 

 pedal glands is behind the appendage at whose base their duct opens, 

 but in front of the maxillary glands. Such a relative position would 

 be difficult to explain if we did not have the developmental stages in 

 which to follow the various changes. 



NERVOUS SYSTEM. 



The nervous system is made up of a very large infra-oesophageal 

 ganglionic mass and an equall}^ small supra-oesophageal portion. The 

 latter can hardlj" be distinguished in the female from the walls of the 

 gullet (sog.,^g. 33). At its anterior end two nerves are given off on 

 either side, one beneath the other. The upper and smaller one (a') 

 goes to the first antenna, but gives off a branch near the base of the 

 antenna which supplies the frontal margin. The lower and larger 

 one (a") goes to the second antenna, but sends a branch to the upper 

 lip. At its posterior end this supra-oesophageal ganglion gives off a 

 large nerve {n, fig. 32) on either side, which runs along the anterior 

 wall of the stomach and supplies the dorsal portion of the head, the 

 frontal gland, and the maxillipedal excretory gland. 



From the anterior end of the large infra-cesophageal ganglion a 

 good-sized nerve trunk (Ih.) runs forward to the base of the lower lip, 

 where it divides and sends a branch to the mandible (md.). 



A slender nerve, given off from the ventral surface of the ganglion, 

 goes to the first maxilla (mx.). Another larger one iinx' .) just behind 

 it supplies the second maxilla, while from the postero-ventral corner 

 a still larger nerve runs to the maxilliped (mxp.). Near the postero- 

 dorsal corner a delicate nerve thread runs down diagonally to the 

 lateral maxillipedal and maxillary glands impg'.). From the corner 

 itself is given oft' the slender nerve which extends backward along the 

 ventral wall of the stomach and close to its fellow from the other side. 

 These ventral nerve trunks {vc.) are no larger than those which supply 

 the maxillipeds, and although they give off branches to the stomach 

 and body walls, to the various muscles, and to the reproductive 

 organs, they show no ganglionic swellings, and no ganglion cells. 



