262 THE LIFE OF CRUSTACEA 



Crustacea (Fig. 82) that resemble Nebalia in having 

 a large bivalved carapace, with a movable beak-like 

 plate in front, a projecting abdomen without con- 

 spicuous limbs, and a pair of large spines at the 

 sides of the telson. Unfortunately, we have almost 

 no knowledge of the structure of the limbs ; but it 

 can hardly be doubted that these very ancient 

 Crustacea were allied to the existing Phyllocarida, 



FIG. 82 Ceratiocaris papilio, ONE OF THE FOSSIL PHYLLOCARIDA. 

 (From Lankester's " Treatise on Zoology," after H. Woodward.) 



a. Traces of antennules ; m, possibly mandibles ; r, rostral plate 



and that they included the forerunners of the higher 

 Malacostraca. 



It is in the Carboniferous epoch, in all probability, 

 that we must look for the origin of most of the 

 existing orders of Malacostraca. In the rocks of 

 this age in different parts of the world there have 

 been found a number of undoubted Malacostraca, 

 nearly all of the shrimp-like form which there is 

 good reason to believe to be a primitive character- 



