36 



Guide to Cnistacca. 



Table- 

 cases 

 Nos. 5-lG, 



Sub-class V. MALACOSTRACA. 



The Ijody consists of nineteen ]inil)-ljeanng sonn'tes (or twenty, 

 if the eye-stalks he reckoned as appendages). A thorax of eight 

 and an abdomen usuahy of six somites are sliarply distinguislied 

 hy the character of the appendages. 



This suh-class is much larger and more varied than any of the 

 others. It may he divided into two series as follows : — 



Series 1. Leptostraca (Ahdomen of seven somites). 



Division 1. PhfjUocarida. 

 Series 2. Eumalacostraca (Abdomen of six somites). 



Division 2. Syncarida. 

 ,, 3. Pcracarida 



4. Hoplocarida. 



5. Eiicarida. 



Fig. 15. 



Nebalia bijxf:, female, from the side (enlarged), a.', Antennule ; a.", antenna; 

 ab.^-ah^', the abdominal limbs ; ad., the adductor muscle joining the two 

 valves of the shell; /., the caudal fori: ; p., palp of maxillula ; r., rostral 

 plate ; t., telson ; 1-7, the seven somites of the abdomen. (From 

 Lankester's " Treatise on Zoology," after Claus.) 



Division 1.— PHYLLOCARIDA. 



Table-case The carapace is bivalved, enveloping hut not coalescing with 



^0- 5- the thoracic somites, and hearing in front a movably articulated 



rostral plate. The eyes are stalked. The last somite of the abdomen 



has no limbs, but the telson carries a pair of appendages forming the 



" caudal fork." The thoracic limbs are flattened and leaf-hke. 



The existing species belonging to this division are few in 

 number but are very widely distributed in all seas. Nehalia hipes, 



