2. SOME CORRELATIONS OF ONTOGENY AND 

 PHYLOGENY IN THE BRACHIOPODA* 



(Plate XIII) 



The parallelism between the ontogeny and phylogeny in 

 the Brachiopoda has been worked out in numerous instances, f 

 To illustrate these, some more or less familiar genera may be 

 taken as characteristic examples. 



Lingula has been shown by Hall and Clarke (^Pal. N. Y., 

 vol. viii, 1892) to have had its inception in the Ordovician. 

 In the ontogeny of both recent and fossil forms, the first 

 shelled stage has a straight hinge-line, nearly equal in length 

 to the width of the shell. This stage may be correlated 

 with the more ancient genus Paterina [=: IpMdea], from the 

 lowest Cambrian. Subsequent growth produces a form re- 

 sembling Obolella, a Cambrian and Lower Silurian genus. 

 Then the linguloid type of structure appears at an adolescent 

 period, and is completed at maturity. Thus Lingula has 

 ontogenetic stages corresponding to (1) Paterina [= Iphidea'], 

 (2) Obolella, and (3) Lingula, of which the first two occur as 



* American Naturalist, XXVII, 599-604, pi. xv, 1893. 



t C. E. Beecher. Development of the Brachiopoda. Part I. Introduction. 

 Amer. Jour. Sci., XLI, April, 1891. 



Development of the Brachiopoda. Part II. Classification of the Stages 



of Growth and Decline. Amer. Jour. Sci., XLIV, August, 1892. 



Development of Bilobites. Amer. Jour. Sci., XLII, July, 1891. 



Revision of the Families of Loop-bearing Brachiopoda. Trans. Conn. 



Acad. Sci., IX, May, 1893, 



Deslongchamps, E. !fetudes critiques sur des Brachiopodes nouveaux on peu 

 connus, 1884. 



Fischer and GEhlert. Brachiopodes: Mission Scientifique du Cap Horn, 

 1882-1883. Bull. Soc. Hist. Nat. d'Autun, V, 1892. 



