JURASSIC ANIMALS. 



435 



make here a decided approach to the Brachyourans or true crabs, by 

 the shortening of the tail in some (Fig. 670) ; and the earliest true 

 crab, Palaeinachus 

 — a spider - crab — 

 has been found in 



the Jurassic of M^ihSkfL H &r 1%/J 



England. The W 



same change — i. e., 

 shortening of the 

 tail — may be seen 

 in the embryonic 

 development of a 

 crab (Fig. 672). 



Insects. — As 

 might be expected 

 from the abundant 



forest vegetation, Fig. 672.— Development of Carcinns mcenas: A, zooea stage; B, mega- 



insects have been lopa stage; c ' final state (after Couch) ' 



found in considerable numbers and variety (Figs. 673-678). Accord- 

 ing to Heer, 143 species of insects are known from the Lias alone. 



Fio. 676. 



Figs. 673-678.— Jurassic Insects: 673. Blattina formosa (after Heer). 674. Glaphyroptera gracilis 

 (alter Heer). 675. .-Eschna eximia (Hager) 676. Libellula. 677. Buprestidium. 678. Hemero- 



bioides giganteus. 



