72 THE VOYAGE OF H.M.S. CHALLENGER. 



The integuments are leathery, with isolated plates of cliitin, of which the following are 

 the principal : — A large central triangular plate on the head (the apex of the triangle being 

 posterior), with a rather ill-defined long narrow plate on each side, leading from the back 

 of the head to the antennse ; the margins of the orbits ; two transversely oval plates on 

 the pronotum ; two large longitudinal oval plates on the mesonotum ; two transverse 

 reniform plates on the metanotum ; a rather ill-defined narrow transverse plate on each 

 side of the mesial line of each abdominal dorsal segment (PI. III. fig. 29). In the alidomen 

 the chitinization of each segment begins at the front margin and spreads backwards. 



In dried specimens the number of abdominal .segments cannot be made out from the 

 shrinking of the integuments, but in two microscopical specimens ten rings can be dis- 

 tinguished behind the reniform plates of the metanotum, wliile in a third example nine 

 rings only can be made out. This difterence in the number may possibly be due to sex, 

 and would seem to indicate that the male has, as its structure suggests, really four genital 

 segments. The podical plates which terminate the body of the adult are present in the 

 larva, but no trace can be found of the peculiar lozenge-shaped plate which precedes them 

 in the adult male. One specimen, which from the- rest of its structure must be regarded 

 as not yet having undergone its final moult, presents all the external genital chai'acteristics 

 of the adult female. 



The antennse are stouter than in the adult and proj^ortionately shorter. The jointlet 

 between the second and third joints is rudimentary, and that between the third and 

 fourth joints is not visible. 



The peculiar tubercles which we have considered to be possil^ly ocelli arc not visible 

 or are more or less rudimentary, according to the age. 



In like manner the dilatation of the apex of the front tibia is more or less unde- 

 veloped according to the age. 



The front tarsus (PI. I. fig. 1, f.t.a) has only one joint, which is cleft and furnished 

 with claws beyond the middle. The other legs are relatively shorter and stouter than in 

 the adult. 



The coloration of the larva is somewhat similar to that of the adult, but the leathery 

 portion of the integuments is often lirown or reddish-brown. 



HALOBATODES. 



No observations of the metamorphoses have been made. 



