164 INVERTEBRATE PALAEONTOLOGY 



pursued their quiet and inconspicuous course, while 

 Cheilostomata were not yet differentiated. 



(G) BRACHIOPODA 



In spite of the rapidly increasing elaboration of other 

 phyla (particularly Mollusca), the Brachiopoda main- 

 tained a position of first importance in the Upper 

 Palaeozoic. The virtual disappearance of the 

 Atremata and Neotremata was fully compensated 

 by the acmaic exuberance of the Productidae among 

 Protremata, and the maintained prominence of 

 Spiriferacea, with awakening specialization of Rhyn- 

 chonellacea, among Telotremata. In the Devonian and 

 Carboniferous periods, Brachiopods still counted as local 

 rock-formers, and they are among the most abundant 

 members of the exiguous British Permian fauna. 



The only group of Atremata to survive the Silurian 

 was the late stock of the Lingulidae. Lingula occurs 

 with some frequency in the Devonian, and is there 

 accompanied by a few other genera. But in the 

 Carboniferous the family declined towards that humble 

 condition in which it still exists. 



The record of the Neotremata is similar. Discinacea 

 persisted in some variety into the Devonian, but became 

 so reduced in Carboniferous times that Orbiculoidea 

 (PI. iv. fig. i) was almost their sole representative. 

 Craniacea are not unknown from the Upper Palaeozoic, 

 but deserve no more flattering mention. 



Among Protremata, the prolific stock of the Orthacea 

 met its doom in the Permian. While typical genera 

 (such as Dalmanella) remained in the Devonian, the 

 majority of Carboniferous forms were clearly phylo- 

 gerontic. Schizophoria, with its spinose surface, and 

 Enteletes with elaborate ornament, illustrate late phases 

 in Orthid evolution. The Strophomenacea, though 



