NO. 5 RHYNCHONELLOID BRACHIOPODS — COOPER 13 



Unfortunately most of the interior characters developed by Buckman 

 are of secondary importance compared with the cardinalia, which he 

 did not develop. He made no effort to learn the details of these fea- 

 tures by serial sectioning as since used by many British authors. 



A necessary task of the future is to determine the cardinalia 

 characters of the Buckman genera and then to sort these genera into 

 families based on these characters. It seems likely that most of Buck- 

 man's genera will prove useful because the exterior features of most 

 of them are distinctive. It will probably be found that some of these 

 ornamentation patterns will be repeated in combination with various 

 cardinalia patterns. The result will be a further, but necessary, pro- 

 liferation of genera, but a considerably better understanding of 

 Jurassic genera will be forthcoming. In this connection the writer has 

 determined the interior features of a number of Jurassic rhynchonel- 

 loids by etching the shell from limestone. These show the cardinalia of 

 Septaliphoria in combination with exterior characters indicating more 

 than one genus. Another interesting feature is variations of the sep- 

 taliphore interior that promise to be of great interest. Silicified Meso- 

 zoic rhynchonelloids occur in South America, Israel, Africa, and else- 

 where, and should be sought and prepared because they offer the best 

 opportunity for understanding interior details. 



Leidhold (1921, 1922) wrote several papers elucidating the interior 

 of the rhynchonelloid shell. His work in 192 1 defined the interior of 

 Septaliphoria and two other genera, but he did not make any strides in 

 classification of these brachiopods. 



Schuchert, in Schuchert and LeVene ( 1929) , took a stride forward 

 in rhynchonelloid classification when he separated the Camarotoechii- 

 dae from the Rhynchonellidae. Unfortunately, however, he did not 

 define the characters of the family. Even with this family divided into 

 three subfamilies Schuchert has many forms of unlike structure clas- 

 sified together. He states that the "Classification into families [of the 

 Rhynchonellacea = Rhynchonelloidea] is not yet satisfactory." No at- 

 tempt was made to subdivide the Mesozoic and later forms except to 

 group them according to geological periods, and to recognize the 

 Dimerellidae of Buckman. 



Thomson (1927, pp. 145-164) discussed Recent and Tertiary rhyn- 

 chonelloids in detail and made many interesting observations on them. 

 He also assigned the genera to two families. The peculiar and primi- 

 tive Cryptopora was assigned to the Dimerellidae where it seems very 

 unhappy and the rest of the genera were put in the Rhynchonellidae 

 where they are likewise out of place. 



