BOPYRUS. 215 



continuous than in the male. The head also is immersed 

 in the anterior segment of the body, its front margin 

 forming a continuous curve with that of the body. The 

 antennae are even smaller and more rudimental than 

 those of the male, the outer pair being apparently 

 only three jointed, and the inner pair only two 

 jointed. 



The mouth is comparatively rudimental in its structure, 

 and is nearly concealed by a pair of oval operculiform 

 foot-jaws, of which the anterior extremity is furnished 

 on its inner edge with a small flattened and biarticulate 

 appendage ; beneath these foot-jaws and near their base 

 are several minute lobes ; the lower lip, on the contrary, 

 is well developed, and forms with the labrum and man- 

 dibles a sort of conical sucker, the mandibles being 

 minute, pointed, and scarcely movable. 



The pereion is broad and flat, and the seven segments 

 of which it is composed are closely soldered together, 

 the lateral portions forming a rather strong border, 

 beneath which are affixed the seven pairs of short, 

 strong, prehensible feet, resembling those of the male 

 in form. They are very small, so as not to extend 

 beyond the sides of the body, and each is furnished 

 at the base with a large plate-like appendage or valve, 

 generally folded inwards, so as to form an incubatory 

 pouch, which does not, however, entirely cover the central 

 part of the underside of the body, leaving a wide open 

 space, which allows the eggs and young to be seen ; the 

 anterior of these plates differs in form from the rest, and 

 seems rather to be transformed into an appendage of the 

 mouth, having its lower extremity obtuse, free and 

 curved (fig. f)- 



The pleon in this sex is broad at the base, but 

 narrower than the pereion, and gradually decreases in 



