XX11 INTRODUCTION. 



large prehensile limbs, which have the penultimate joint extremely 

 thick and powerful, and the terminal joint swollen at the base, 

 slender and pointed at its extremity, and capable of beiug 

 folded against the preceding joint in the same way as the blade 

 of a pocket-knife shuts up in its handle. Succeeding the large 

 pair of prehensile appendages are three smaller pairs (Fig. vii., 

 3, 4, 5, Fig. viii., 3 t), also prehensile and very similar to one 

 another in appearance, having the proximal joints rather slender 

 and laterally compressed, the propodos ovate and flattened, and 

 the dactylus shutting down on its anterior or lower border. 

 Behind there are three pairs of non-prehensile legs (Fig. vii., 

 6, 7, 8, Fig. viii., 6 t) divided into endopoditic and exopoditic rami. 

 The following six segments may be regarded as corresponding to 

 the abdomen of the Prawn ; the first five are each provided with 

 a pair of swimmerets (Fig. vii., a, b, c, d, and Fig. viii., lpl) consist- 

 ing of a basal portion or protopodite, and two broad hair-fringed 

 rami, representing respectively the endopodite and exopodite. 

 The last segment bears a large pair of appendages (Fig. vii.,/') 

 placed at the side like the corresponding appendages in the 

 Prawn, and consisting of a basal protopodite and two hair-fringed 

 rami, the outer of which is spinose, and is provided at its 

 extremity with a separate ovate terminal portion. Following 

 the last segment of the abdomen is the large sculptured telson 

 (Fig. vii., so). 



The organs of respiration of Gonodactylus consist of bunches 

 of short filaments attached to the abdominal appendages. (Fig. 

 viii., lpl, br) The heart, unlike that of the Prawn or the Crab, is 

 an elongated tube extending through the thorax and -abdomen, 

 and provided with five pairs of slits the venous ostia. The 

 stomach is less complex than in the Prawn or the Crab, and the 

 intestine is a straight tube into which ten pairs of hepatic coeca 

 open. The nervous system consists of a head-ganglion or brain, 

 of a large hypopharyngeal ganglion composed of the amalgamated 

 anterior thoracic ganglia, of three smaller ganglia, one in each 

 of the last three segments of the thorax, and of six large 

 abdominal ganglia. 



During its development the GTonodactylns passes through 

 curious larval (Zocea) stages, in which it is provided with a large 

 carapace armed with spines. 



