23H HISTORICAL PALAZAONTOLOGY. 
tionships of which appear to be with some of the living 
Butterflies of Tropical America. 
Coming to the Mollusca, the folyzoans, numerous and 
Fig. 164.—Exryon arctiformis, a ‘ Long-tailed Decapod,” from the Middle 
Oolites (Solenhofen 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 
Paleozoic deposits, but they are still individually numerous. 
The two ancient genera Leptena (fig. 165, a) and Sfirifera (fig. 
165, 4), 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 Zerebratula (fig. 165, ¢, ¢, /) 
and Rhynchonella. (fig. 165, 2), both of which are represented 
by living forms at the present day. The Zerebratule, in par- 
ticular, are very abundant, and the species are often confined 
to special horizons in the series. 
Remains of Lzvalves (Lamellibranchiata) are very numerous 
