2G4 AMPIIIPODA STOMAPODA DECAPODA. 



nearly equal in size, eacli supporting a pair of feet ; and the 

 same number of rings in the abdomen. It comprises the 

 ONISCIDJE, which are terrestrial. Some species are found 

 fossil in amber, from the superior tertiary beds. 



The SPHJEEOMID^: contains all the marine forms allied to 

 the preceding. The fossil genera are considered to differ 

 from those living in our own seas. From the Oxford stage 

 of the oolites of Bavaria, Count Minister has obtained Alms, 

 Urda, Norna, Sculda, RecJcur, and Naranda. Arclicconiscus 

 is found in the wealden of England and France, and Palceo- 

 niscus in the tertiary beds of Paris. 



Order AMPHIPODA. Have sessile eyes; the branchiae 

 are attached to the seven thoracic feet ; the abdomen is com- 

 posed of seven segments, of which the four last are modified 

 to form an organ for leaping or swimming. Belonging to 

 this order is the genus Typltis, from the older tertiary strata 

 of America. 



Order STOMAPODA. Have the eyes pedunculated and 

 moveable. To this group the Squillidce belong. The impres- 

 sion of a fossil species of Squilla has been found in the 

 tertiary beds of Monte-Bolca. 



Order DECAPODA. Have the head and thorax covered 

 by a hard shield, the eyes pedunculated and moveable, the 

 branchiae enclosed in the thorax; they have five pair of 

 thoracic feet, of which the anterior pair are formed into 

 powerful forceps. There are six pairs of mouth-organs or 

 jaws. It comprehends the following families. 



The PALCEMONIDJE, or Prawns, contain a great many 

 existing genera. Count Minister has described, from the 

 Oxford stage of the Bavarian oolites, the following fossil 

 genera: (Eger, Antrimpos, Bylgia, Drobna, Kcelga, Udora, 

 Z)usa, Hefriga, Boinbur, Blaculia, Elder, Sauna, Saga. 

 To these may be added a fossil species of Crangon from 

 the upper lias of Normandy. 



The ASTACIDJE, or Lobsters, form an extensive family in 

 our modern seas. The fossil genera, which are numerous in 

 the oolites, may be separated thus : Coleia is found in the 

 liasic stage. GlypJicea in the inferior oolite. Magila, OrpJinea, 

 Brisa, Brome, Bolina, Aura, Pterochirus, Klytea, Eryma, 

 Megachirus, are chiefly from the Oxford stage of Bavaria. 



