No. 26.] 



ARTHROSTRACA OF CONNECTICUT. 



27 



ized processes of the integument, whose exact functions are still 

 largely conjectural. When a foreign chemical substance is placed 

 in a vessel containing Amphipoda, the antennae are waved vigor- 

 ously, which may point towards the conclusion that on these 

 appendages are smelling or tasting organs. The delicate thread- 

 like setae noted frequently on the principal flagellum of the first 

 pair of antennae are called olfactory hairs. The calceoli, which 

 occur in forms like Calliopius, are conical vesicles attached by 

 their apices to the general surface of the skin. They have been 

 called by Leydig " slipper-shaped " structures, but with greater 

 propriety they might be compared to wine glasses. Their func- 

 tion is wholly unknown. 



INTERNAL ANATOMY. 



The nervous system consists of two symmetrical ganglionic 

 chains, united at intervals by commissures, and lying on the 



postenoraarto 



\ Jrepato-pancreat 



fesf/s 



tfomacfr 



a/ifer/oraorta 



FIG. 2. Internal Anatomy, after Stebbing. 



ventral side of the alimentary canal, except at the extreme ante- 

 rior end, where the ganglia are on the dorsal side (Fig. 2). 

 The supraesophageal mass is made up of two halves, separated 

 by a deep median groove, and consists of two large cerebral lobes, 

 as well as a pair of ganglia, which give rise to the optic nerves, 

 and another pair giving rise to the antennal nerves. Beneath 

 the esophagus and connected with the brain by commissures 

 around it, lies the subesophageal mass, which gives 'off nerves 

 to the mouth parts, and represents the consolidated ganglia of 

 the segments to which the mouth parts belong. The sub- 

 esophageal ganglia are continuous posteriorly with the sub- 

 intestinal ganglionic chain. This consists of a pair of ganglia, 



