Reports and Proceedings — Royal Microscopical Society. 381 



IV. CIREIPEDIA. 



(Sessile) 

 'BslsL-Qxidi {Brachylepas) Cretaceous to recent. 



(Pedunculated) 

 Lepadidse ( Turnkpas) ... ... Silurian to recent. 



B.— AEACHNIDA. 



SCORPIONID^. ■« 



(Scorpions) Silurian to recent ; world-wide 



distribution. 



Palceophonus Up. Sil., Scotland, Gotland,. 



and IlKnois, U.S. 



Eophry7ius ... ... ... ... Carboniferous only. 



C— MYEIOPODA. 



^«r^/toJma and allies Coal-measures to recent. 



D.— INSECTA. 



FalcBodiotyopfera. 



Blatta ... ... ... ... (Silm'ian?) to recent.'t: 



Huger eon, etc. ... ... ... Permian to recent. 



Orthoptera ... ... ... ... Coal-measures to recent. 



Neuroptera ... ... ... ... Ditto. 



Summary. — And now, " let us hear the conclusion of the whole 

 matter." 



The whole history, since the beginning of life on the earth, shows 

 a steady upward tendency (in fact, Evolution) in life as displayed 

 in the Geological Kecord. 



Extinct Groups. — Some forms appear, attain a more or less 

 important position on life's stage, and then die out completely. 



Of such are the once abundant Gkaptolites, which had their 

 beginning in the Cambrian, their maximum in the Ordovician and 

 Silurian, and then disappeared. 



The Tkilobites, which began in the Cambrian, attained their 

 maximum in the Silurian, lived on into Carboniferous times, and 

 then disappeared. 



The Merostobiata (Fterygotus, JEurypteriis, Stylonurus, etc.) began 

 in the Silurian, attained their maximum, lived on into the Devonian 

 and Carboniferous periods, and then became extinct. 



Persistent Groups. — Again we have persistent forms of which we 

 seem to see neither the beginning nor the ending. 



Of these we may name the Protozoa, embracing the Eadiolaria 

 and the Foraminifera, both persistent in rocks of all ages and well 

 represented at the present day. 



The PoRiFERA (Sponges), which, though materially differentiated 

 in the course of geological ages, have lived on through all time. 



The Crinoidea (Sea-lilies), represented from Silurian times to the 

 present day, but not nearly so abundant as in Paleeozoic times. 



The Starfishes (Asteroidea and Ophiuroidea), both persistent 

 types from Silurian (or earlier) times to the present. 



The Annelida, again, are met with in all strata and also living. 



The Brachiopoda, beginning in the Cambrian, enormously 

 developed in Silurian, Devonian, Carboniferous, and Secondary 

 deposits, and still surviving in diminished numbers in modern seas. 



