224 OUR COMMON BRITISH FOSSILS. 



coiled arms for locomotive purposes. Such was the 

 origin of the term Brachiopoda, or " arm-footed." 

 And, although Professor King endeavoured to change 

 the name to Palliobranchiata (or " mantle-gilled "), the 

 latter somehow has not " stuck." Suffice 

 it to say, therefore, that the long arms 

 of the Brachiopoda so distinctive a 

 feature in their anatomy and physi- 

 ology are only labial appendages to 

 the mouth, bringing food by means of 

 their currents, and air as well ; but 



Fig. 190. Lingula . . '. 



(Silurian forma- are never employed as locomotive 



tion). 



organs. 



The young of the Brachiopoda^ like those of such 

 well-known bivalves as the common oyster, are free- 



FJ^. i 9I ._ Lingula Lewisii Fig. ig-z.Leftana transversals 

 (Silurian formation). (Silurian). 



swimmers. In this stage they are believed by 

 some to show evidences of annelid affinity just as 

 Mr. Harmer has recently demonstrated that young 

 Polyzoa show affinities with the Rotifercz. It is 

 interesting thus to see the hitherto unstudied stages 

 of embryological development enabling the naturalist 

 to join hands across a space which the boldest investi- 

 gator would not have dreamed of half a century ago ! 



