Crangon and Galathea. 51 



nying respiratory organs, the latter being supported on the cosce of the cheli- 

 peds. The coxte are soldered to each other and their respective somites, and 

 concealed beneath the lateral expansion of the mandibular segment. 



Fifteenth to nineteenth somites are fully developed, and each generally 

 bears a natatory foot (pleopod), made up of coxas, basis, and ischium, the 

 00X32 soldered by its edge to the somite; the basis, in the male, and in the 

 female the first three limbs, furnished with a ciliated appendage ; the ischium 

 multiarticulate, and ciliated along its edges : these in the females bear the 

 ova. 



Twentieth — well developed ; appendage natatory ; coxa3 soldered ; basis 

 with a lamellar appendage, which, with the flattened ischium and the telson, 

 constitute the so-called tail-plates. 



Twenty-first somite (telson) — trigonal narrowed, chitinous, unappendiculate, 

 bearing a series of spines along its borders. 



All the true Crangons have the first pair of chelipeds (R 10), with the 

 dactylos (d) long and curved, folding down on the internal angle of the propo- 

 dos (p), which is prolonged into a slender tooth. The second pair of chelipeds 

 (R 11) are didactyle, the dactylos articulated to the inner side of the propo- 

 dos, the outer superior angle of which is developed into a long, rounded, mo- 

 derately strong tooth, equalling the dactylos in length, and opposing it. This 

 pair of chelipeds is subject to much variety in the several species, as regards its 

 proportional length and thickness. 



The remaining pairs of chelipeds are simple, the dactylos arising from the 

 extremity of the propodos. 



The auditory antennae are inserted in a line above the olfactory. Their 

 peduncle is four-jointed, the last joint furnished with a club-shaped multiarticu- 

 late filamentous appendage, and terminating itself in a filament which is multi- 

 articulate. 



The olfactory antennas are four-jointed, the basis supporting a squamiform 

 appendage ; a long multiarticulate filament terminates each of the antennse. 



The maxillipeds of the ninth somite are subpediform, and six-jointed, the 

 dactylos being apparently wanting. 



The eyes are free, uncovered above, and unappendiculate. 



