234 HISTORICAL PALEONTOLOGY. 



tionships of which appear to be with some of the living 

 Butterflies of Tropical America. 



Coming to the Mollusca, the Polyzoans, numerous and 



Fig. 164. Eryon arctiformis, a "Long-tailed Decapod," from the Middle 

 Oolites (Soleunofen Slate). 



beautiful as they are, must be at once dismissed; but the 

 Brachiopods deserve a moment's attention. The Jurassic 

 Lamp-shells (fig. 165) do not fill by any means such a pre- 

 dominant place in the marine fauna of the period, as in many- 

 Palaeozoic deposits, but they are still individually numerous. 

 The two ancient genera Lept&na (fig. 165, a) and Spirifera (fig. 

 165, b), dating the one from the Lower and the other from the 

 Upper Silurian, appear here for the last time upon the scene, 

 but they have not hitherto been recognised in deposits later 

 than the Lias. The great majority of the Jurassic Brachiopods, 

 however, belong to the genera Terebratula (fig. 165, c, e, f) 

 and Rhynchonella (fig. 165, d\ both of which are represented 

 by living forms at the present day. The Tercbratulce, in par- 

 ticular, are very abundant, and the species are often confined 

 to special horizons in the series. 



Remains of Bivalres (Lamellibranchiata) are very numerous 



