44 



THE LIFE OF CRUSTACEA 



Lobster — namely, nineteen pairs (or twenty, if the eye- 

 stalks be included). They also agree in the very 

 important character that the trunk limbs are divided 

 into two sets, thoracic and abdominal, the former of 

 eight, and the latter of six pairs. 



The first order of the Malacostraca, the Neba- 

 LIACEA, comprises a few Crustacea of small size, 



ad P- 



Fig. 15 — Nebalia hipes. Enlarged. (From Lankester's 

 " Treatise on Zoology," after Claus.) 



a', Antennule ; a!', antenna ; ab^-ab'^, the abdominal limbs ; ad, 

 muscle joining the two valves of the shell ; /, tail-fork ; p, palp 

 of maxillula ; r, rostral plate ; t, telson ; 1-7, the seven somites of 

 the abdomen 



which differ in some very important characters from 

 all the other orders. Nebalia hipes (Fig. 15), which 

 occurs on the southern coasts of the British Isles, has 

 a large bivalved carapace enclosing most of the 

 limbs. In front, a small " rostral plate " is joined 

 to the carapace by a movable hinge, and partly 

 covers the stalked eyes. The eight pairs of thoracic 



