506 CRUSTACEA MALACOSTRACA. 



an accessory flagellum which divides again (as in some Caridea) 

 into two flagella, of which the outer is somewhat flattened, and 

 beset with olfactory hairs. A movable plate, recalling that of 

 Nebalia, projects from the front of the dorsal shield over this 

 segmented region of the head. 



The question arises Is the segmentation of the front of the Stomatopod 

 body the remains of a primitive segmentation, or is it secondarily acquired ? 

 The absence of a corresponding segmentation from the preoral part of the 

 body of the entomostracan groups points to the latter conclusion. 



The posterior antenna (A") is biramous, the endopodite ending 

 in a flagellum, and the exopodite consisting of a large oval scale. 



The preoral region is considerably elongated. The anterior 

 and posterior lips are well developed, and the mandibles, lying 

 between them, bear a slender palp. The second pair of maxillae 

 have a peculiar shape, with a lobed inner and outer border as 

 in larval Penaeidea. 



The region of the body to which the five maxillipeds are attached 

 presents three tergal sclerites, which correspond to the three posterior 

 appendages. In front of the anterior sclerite a membranous tract uniting 

 it with the base of the dorsal shield, lies dorsal and anterior to the 

 insertion of the great second maxillipeds. Hence it does not appear 

 that more than the first thoracic segment is represented with the head 

 region in the shield of the adult. In the larva the shield is entirely cephalic. 



The maxillipeds are armed with prehensile claws, so shaped 

 that the pointed terminal joint folds, like the blade of a pocket- 

 knife, on its predecessor, and the limbs are so disposed that 

 these joints are directed forwards and not backwards, as in 

 Amphipods. The second pair, which are by far the largest, are the 

 chief weapons of these exceedingly pugnacious animals. Eachmax- 

 illiped bears on the outer side of its basal joint a stalked discoidal 

 branchial lamella (epipodite). The three succeeding appendages 

 (B'-B"'} are biramous and bear short styliform multiarticulate 

 rami on their third segments, and their flattened terminal surfaces 

 are thickly clothed with setae, like a hare's foot. According to 

 Claus the shorter rami are the endopodites and the longer exopo- 

 dites, and the stem of the appendage is two-jointed in the larva. 



The gills on the large swimming feet of the abdomen consist 

 of unbranched filaments disposed in transverse rows along the 

 branches of an axis, which is inserted on the inner margin of the 

 base of the exopodite. The uropods are without gills and, 

 directed backwards, form with the distinctly jointed telson a 

 powerful caudal fin. 



