774 
ME. H. N. MOSELEY ON THE STEUCTURE AND 
head-processes (m) grow right down over their bases ; the superior and inferior median 
projections (labrum and labium) become more prominent, the labrum covering the 
mouth gradually over. At the bases of the second pair of members (oral papillae) are 
seen through the skin the openings of the ducts of the slime-glands, which will eventu- 
ally terminate at their tips. 
A defined secondary cavity or mouth is already shut in around the true mouth by the 
rising up of surrounding structures. The head-processes become lengthened or raised 
into tumid folds on their inner margin, the future tumid lips of the adult ; they grow on 
and fuse with the structures about the bases of the oral papillae (Plate LXXV. figs. 9&10), 
and the first pair with their developing claws become shut entirely within the secondary 
mouth. The head-processes extend their inner margin up on to the front of the head, 
where there rise up tumid processes which swell up above the labrum, and eventually 
shut it out from view, join the swellings on the inner margin of the head -processes, and 
thus complete the characteristic tumid lip-ring of Peripatus. The latest stage observed 
is seen in fig. 10. A sulcus persists in the lips of the adult Peripatus, which probably 
represents the line of separation between the lips of the mouth-processes and the struc- 
tures with which they fuse. The antennae become gradually more slender in proportion 
to their length, and acquire a greater and greater number of joints. The number of 
joints in the antennae is a sure indicator of the stage of development of the parts of the 
mouth. The most developed embryo observed possessed seventeen joints in the antennae ; 
in the adult certainly as many as thirty are present. It would be of interest to observe 
whether the embryos at the time of birth possess the full number of joints in their 
antennae. 
The members wkich become ambulacral in function and the oral papillae, become in 
development at first two- or three-jointed and eventually five-jointed. They thus have 
the number of joints so remarkably constant in insects. In the adult five joints can 
also be made out in the ambulacral members, the first joint or coxa being very long 
proportionately to the rest, and marked with closely approximated rings. The other 
joints are short, except the last claw-bearing joint or tarsus, which is fine and neat like 
that of many insects. In Scolopendra the first pair of feet, modified into prehensile 
jaws, has five joints, including the claw, and perhaps the more numerous joints of the 
other feet are derived by secondary jointing from a like number. 
The claws are developed at the bottom of depressions or invaginations formed at 
ends of members, and are derived from the epidermic layer (Plate LXXV. fig. 12). 
They appear late, having been first observed in the latest stage which was found. The 
mouth-claws, or jaws, are represented in fig. 11, from an embryo in the stage shown 
in fig. 10. I have no papers at hand in which the development of the parts of the 
mouth in Myriopods or Insects are described at length, but am only able to refer to 
Newport’s conclusions on the subject in his well-known papers already quoted*. 
Newport, Linn. Trans, vol. xix. 1843, p. 265. 
