664 



ARTHROPODA 



SUB-KINGDOM VII 



other respects approaches the Astacidae. Carapace solid and roughened, cervical suture 

 deep ; sternum narrow ; legs monodactyle, the first pair being the largest, and in some 



cases sub-ch elate. Pemphix, v. Meyer (Fig. 1388), 



v occurs in the Muschelkalk ; Lithogaster and 



Glyphaea, v. Meyer (Fig. 1389), range from the 

 Trias to Cretaceous ; Pseudoglyphaea, Oppel, is 

 Jurassic ; and Meyeria, M'Coy, Neocomian. 



(6) The Astacidae are distinguished by the 

 possession of a narrow sternum ; ch elate 

 appendages, of which the first pair is very 

 strongly developed, and an antenna! scale. Both 

 salt- and fresh -water forms occur. Eryma, v. 

 Meyer (Fig. 1390), Pseudastacus, Stenochirus, 

 Etallonia, Oppel, are found in the Lithographic 

 Slates. Isolated chelae of Magila (Fig. 1391) are 

 abundant throughout the Jura. Enoplocytia, 

 M'Coy ; Nymphaeops, Schliit. ; Hoploparia, 

 M'Coy ; Oncoparia, Bosquet ; and Palaeastacus, 

 Bell, occur in the Upper Cretaceous of West- 

 phalia, Bohemia, and England. Homarus, Milne- 

 Edw. ; Nephrops, Leach ; and Astacus, Fabr., 

 range from the Upper Cretaceous to Recent. 



(7) The Thalassinidae 

 JJL have the abdomen much 



elongated, carapace with 

 j||j two longitudinal sutures, 



anterior feet the largest 

 FIG. 1391. and chelate, and whole 



body except the chelae 

 enclosed in a thin integu- 

 ment. Numerous chelae 

 referable to Callianassa, 



Leach (Figs. 1392, 1393), are found in the Cretaceous and Tertiary. Thalassina, Latr., 

 is Tertiary and Recent. 



(8) The Galatheidae differ from the last family in having the broad abdomen 

 slightly recurved below ; cephalothorax strongly calcified and with numerous transverse 



Eryma 

 graphic Slates ; 

 (after Oppel). 



FIG. 1390. 



na, Germ. sp. 

 Solenhofen, Bavaria. 



Litho- 



Vi 



Magila 

 Quenst. sp. 

 Soflingen, 

 Chela. 



FIG. 1392. 



Callianassa, Archiaci, M.-Bdw. Turuniai 

 dragon. Var. (after Milne-Edwards). 



FIG. 1393. 



Mont- Callianassa antiqua, Otto. Turonian ; Turnau, 

 Bohemia. Right chela. 



furrows ; posterior pair of feet very small and delicate. Fossils are extremely rare, 

 and consist only of chelae of Galathea from the Upper Cretaceous of Faxoe. Equally 

 rare are the chelae of Pagurus, belonging to the Paguridae or Hermit Crabs, described 

 from the Eocene of Hungary. 



