594 BRITISH ORIBATID^. 



ANATOMY. 

 The Internal Anatomy of thp] Nymphs. 



The internal organization of the Orihatidce during 

 their immature stages in the main resembles that of the 

 adults, and consequently there is but little to add here 

 to the description already given of the more important 

 inner organs of the latter in Chapter X (vol. i). There 

 are, however, some very considerable points of diff(3r- 

 ence, and others which, although of lesser value, are 

 still worthy of notice. 



To adopt the same order of dealing with the various 

 systems as was adopted in the case of the adults : — 



The Alimentary Canal consists of parts similar to 

 those composing the canal of the imago, and the whole 

 of the digestive organs are practically identical with 

 those of the sexually mature creature. The nymphal 

 stage, however, is essentially the period of growth, it 

 is not surprising, therefore, that the organs connected 

 with the procuring and absorption of food should 

 take an even more prominent part in the organism 

 during this time than in the later portion of life ; 

 accordingly we find the whole of the canal largely 

 developed in the nymphs, forming by far the most 

 important group of organs. There is but little to be 

 said usefully respecting it, as the distinction from the 

 adults consists in size, not in structure, and naturally 

 the size varies considerably in different species; it 

 may, however, be pointed out that the great caeca of 

 the ventriculus are even larger, and more strongly 

 developed in the nymphs than in the adults; and this 

 would probably form an additional argument in favour 

 of their glandular, or partly glandular, nature, as sug- 

 gested in vol. i, because all, or almost all, of the 

 glandular structures are strongly developed in the 

 nymphs. Thus the preventricular glands, which really 

 are modified anterior caeca of the ventriculus, and also 



