496 



ARACIINIDA. 



the Mites and Spiders amongst the AracJmida, although they possess 

 a greater number of appendages than either, inasmuch as the males 

 have an accessory pair of legs, used in carrying the eggs (tig. 389, A 

 B}. They are small animals with a conical suctorial proboscis and 

 rudimentary abdomen (reduced to a tubercle) ; and they live in the 

 sea, and crawl slowly about amongst the sea-weeds. There are four 

 pairs of very long, many -jointed legs, which contain tubular diver- 

 ticula of the stomach and the sexual glands. There are no tracheae. 

 On the other hand, there is a well-developed heart with an aorta 



FIG. 300. Annnonrn jnitjnngannifltt (rjpne miiinnl). Da, prolongations of alimentary 



canal into the U-^F. 



and several lateral ostia. Above the brain lie four small simple 

 eyes. There is a considerable ventral chain, composed of several 

 ganglia. The eggs are carried about on the accessory pair of legs on 

 the thoi-ax of the male (fig. 389) till the larvae are hatched. 



Pyi/noffimum Jitfuralc 0. Fr. Miiller. North Sea. Pkoxiehilidium Edw., 

 Ammnthi-a Leach, A. jn/gnogonoides Quatr. (fig. 390). 



TAKDIGRADA.* 



The Tardigrada constitute a second group, which is often separated 

 as a distinct order. They are small mite-like Arachnida, and may 



* Doyerc, " Mdmoire sur les Tardigraclcs." Ann. tic* >>'<'. Xttt., II C S6r., Tom. 

 XIV., XVII.. XVIII. C. A. S. Schultze. ''MacrobiotusHufelandii, etc,"Berolini 

 1834.' C. .S. Schultzc, ' Echiuiscus Bcllennanni," Bcrolini, 1S10. Dujardin, 



