i68 



THE CRUSTACEA 



divided by a suture. In Praeanaspides (Fig. 98), recently described 

 by Dr. H. Woodward from the English Coal-measures, the seg- 

 mentation of the body agrees with that of Anaspides, and exopodites 

 are certainly present on some of the thoracic limbs. Other genera 

 are Palaeocaris, Acanthotelson, and Gasocaris. 



Fio. 97. 



Urnnectcs \ = Gampson'>tx]Jiml>riatiis. a', antennule ; e, supposed eye ; ex, traces of exopodites 

 on thoracic limbs ; I, enlarged thoracic limb, probably the second ; /, first thoracic somite. 

 (After Jordan and von Meyer.) 



AFFINITIES AND CLASSIFICATION. 



The existing genera of Syncarida present characters which 

 indicate for them a very isolated place among living Malacostraca, 

 while suggesting more or less remote affinities with widely divergent 



FIG. 08. 



Praeanaspides prnecitrsor, from the Coal-measures of Derbyshire. 

 (From H. Woodward in Geol. Meg.) 



groups. They have retained characters of the primitive caridoid 

 type in the tail-fan, the biramous antennules, the scale-like exopodite 

 of the antenna (in Anaspides), and the natatory thoracic exopodites. 

 With the loss of the carapace, however, the segmentation of the 

 body comes to resemble that of the Isopoda and Amphipoda, though 

 the demarcation of the first thoracic somite from the head (if this 



