TYPE CRUSTACEA. 409 



segments are fused with the carapace, though it covers iu 

 several others. 



The antermules consist of an elongated three-jointed basal 

 portion bearing three rnauy-jointed flagella, while the anten- 

 nae are generally shorter, the exopodite being represented by 

 a large scale. The maxillae are comparatively small, and the 

 appendages of the five anterior thoracic appendages are 

 crowded forwards and are termed maxillipeds, being limb- 

 like structures destitute of exopodites, but possessing well- 

 developed epipodites, and with the terminal joint capable of 

 flexion upon the next succeeding one. The second maxilli- 

 ped is especially long and large, and with its strong terminal 

 and penultimate joints forms a very efficient weapon for secur- 

 ing prey. The three posterior appendages of the thorax are 



OC 



FIG. 1^6. Squilla mantis (from LEUNIS). 

 a 1 = autenuules. pm = maxillipeds. 



a 2 antennae. p = thoracic limbs. 



oc = compound eyes. pa, = abdominal limbs. 



slender birarnous structures, the somewhat stronger abdomi- 

 nal appendages being also biramous and somewhat lamellar 

 swimming-feet. The last pair are especially enlarged and di- 

 rected backwards, forming with the telson the strong tail-fin. 



Bunches of branchial filaments occur upon the outer lamel- 

 lae of the abdominal appendages with the exception of the last 

 pair. The heart is much elongated, extending from the ante- 

 rior thoracic region as far back as the fifth abdominal seg- 

 ment and possessing numerous pairs of ostia. It is prolonged 

 anteriorly and posteriorly into aortae and gives off laterally 

 in each segment a pair of arteries. 



The Stomatopods are all marine and pass through a com- 

 plicated series of metamorphoses during development. Some 

 of the principal genera are Squilla (Fig. 186), Lysiosquilla, ami 

 Gonodadylus. 



