CRUSTACEA. LEPTOSTRACA 



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ORDER I. LEPTOSTRACA (PHYLLOCARIDA) 



The Leptostraca differ in several respects from all the 

 other Orders of the Malacostraca, and possess characters 

 which connect them with the Phyllopoda. Only four 

 genera are now living, of which the commonest is Nebalia; 

 they are small shrimp-like Crustacea, with the body 



Fig. 138. Paranebalia longipes, Recent. (After Sars.) x 13. a, ros- 

 trum ; b, eye ; c, antennule ; d, antenna ; e, mandibular palp ; /, last 

 thoracic leg ; g, first abdominal leg ; h, k, rudimentary limbs of fifth 

 and sixth abdominal segments ; I, caudal fork ; m, cephalic part of 

 carapace ; ??, mandible ; o, second maxilla ; p, adductor muscle of 

 carapace; q, first maxilla; r, first segment of thorax; s, ovary; 

 t, last segment of thorax ; u, first abdominal segment. 



laterally compressed. A large bivalved carapace (fig. 

 138, m) covers the head, the thorax, and some of the 

 abdominal segments, but is united to the head only ; the 

 two valves are connected by an adductor muscle (p) just 



