CRUSTACEA. STOMATOPODA 327 



ORDER VIII. STOMATOPODA 



In the Stomatopocls the body is long, and flattened 

 dorso-ventrally ; the cephalo-thoracic shield is short and 

 does not cover the four posterior thoracic segments. At 

 the front of the head there are two, small, movable seg- 

 ments which are not covered by the shield ; the first bears 

 the stalked eyes, the second bears the antennules. A 

 rostral plate is articulated to the front of the cephalo- 

 thoracic shield. The five anterior pairs of thoracic append- 

 ages are directed forwards as maxillipedes ; the three 

 posterior pairs are slender biramous legs and are directed 

 downwards. The abdomen is much larger than the an- 

 terior portion of the body ; its five anterior appendages 

 bear gills, and the sixth pair form with the broad telson 

 a strong tail fin. 



Squilla is the best known genus of this Order. All 

 the forms are marine and live in shallow water. The 

 Stomatopods are very rare as fossils. A few Crustacea 

 found in the Carboniferous (e.g. Necroscylla) have been 

 referred to this group ; but undoubted representatives, 

 belonging to the genus Sculda, occur in the Solenhofen 

 Limestone (Upper Jurassic). Squilla has been found in 

 the Chalk of Lebanon and in some of the Eocene forma- 

 tions (London Clay, etc.). 



ORDER IX. DECAPODA 



The Decapoda include lobsters (fig. 143), cray-fishes, 

 crabs, etc. The cephalo-thoracic shield (a — c) is large 

 and well developed, and usually covers all the segments of 

 the thorax (b — c) ; frequently it is marked out into an 



