SUBCLASS II 



EÜCRUSTACEA— EUCARIDA 



761 



affinities vvitli the Reptantia. The extinct genus Aeyer (Fig. 1475), whicli has 

 representatives in tlie Trias and also in tlie Solenliofen Lithograjjliic Stone, agrees 

 w'ith the Recent genera in having the third pair of legs chelate and much larger 

 than the first. It is, in all probability, a primitive member of this tribe. 



Representatives of the Caridea are not known with certainty earlier than the 

 Kinimeridgian, though some Carboniferous fossils have been described as having the 

 enlarged side-plates of the second abdominal somite, which are characteristic of this 

 tribe. In the Solenliofen Stone numerous genera occur, some of which, such as Udora 

 Münster, and Udorella Oppel, have exopodites on the thoracic legs, a primitive 

 character suggesting affinity with the Recent family Acanthephyridae. Other 

 Solenhofen genera, in which these exopodites appear to be wanting, are Blaculla^ 



Fig. 1475. 

 Aeger tijndariiis (Schloth.). Upper Jura (Lithographie Stone) ; Eichstädt, Bavaria. 2/3. 



Hefriga and Eider Münster. The Recent deep-sea genus Oplophorus Milne Edwards 

 (Acanthephyridae) has been identified, with considerable probability, in the Upper 

 Cretaceous of Westphalia. Some Caridea are found in fresh-water Tertiary deposits, 

 as for example Homelys von Meyer, from the Miocene of Oeningen ; but it is 

 impossible to say what relation they bear to the groups of Recent Caridea that have a 

 fresh-water habitat. 



Suborder B. REPTANTIA Boas. 



Body often depressed, rostrum often ahsent^ small and depressed if present. First 

 somite qf abdomen distinctly smaller than the others. Legs stout, without exopodites, 

 the first pair usually much larger than the others. First five pairs of abdominal 

 appendages commonly small, not used for swimming. 



§ 1. Palinura. 



This section consists of lobster-like forms with the rostrum very small or often 

 absent, with the carapace fused at the sides with the epistome, and the exopodite of 

 the uropods not divided by a distinct suture. It includes two tribes (1) the Eryonidea 

 and (2) the Scyllaridea (or Loricata). 



The Eryonidea comprise, among living forms, only a small number of genera 

 such as Polycheles Heller, and Willemoesia Grote, which have chelae on the first four or 



