I90I S. S. BUCKMAN— BRACHIOPODA 239 



curvifi'ons stock takes on characters which have hitherto 

 been regarded as special to the fimbria group. Now I 

 have to point out another case in the same genus in which 

 the fimbria character is taken on by a shell earlier in the 

 Pseiidoglossothyris series, because it had hardly commenced 

 to show dorsal sulcation before it added fimbriation. And 

 since these notes were written Mr L. Richardson has 

 brought to my notice a fossil of another group, the maxil- 

 lata series of Terebratula, which shows similar indications 

 of developing fimbriae. 



Thus in the Cotteswold district, in rocks of about the 

 same date, there are five independent developments of 

 the same character among species of Terebratulidae. 



It may be noted, in passing, that one of the recent 

 Brachiopods, JMagellania flavescens shows the same de- 

 velopment of fimbriae, and is remarkably like T. fimbria in 

 every way. The likeness is an excellent instance of hetero- 

 chronous homoeomorphy. And in the Lias a fimbriate 

 series of the MagcUanidce forms the genus Fimbriothyris. 



As may be easily imagined, homoeomorphy has led to 

 many errors in identification of species — particularly 

 among Brachiopoda. When the homoeomorphous species 

 are nearly related — two stocks of Terebratiilce, for in- 

 stance — much excuse may be made. When, however, the 

 species belong to two families, Terebratulidae and Magel- 

 lanidae (Waldheimiadae), whose structural details, espe- 

 cially the internal arrangements, are quite distinct, then 

 the confusion of two species of these families under one 

 name becomes serious. Yet such confusions have been 

 made even by the great authority on Brachiopoda, Thos. 

 Davidson, as may be seen in his work on the Jurassic 

 species. It is the object of the present paper, in part, to call 

 attention to the mixing of examples of two families under 

 one name, to figure other remarkable homoeomorphous 



