ON THE GENUS SYRINGOPLEURA SCHUCHERT 1 



GEORGE H. GIRTY 



The genus Syringopleura has recently been proposed 2 for a 

 brachiopod of the Spirifer group. It is typified by Syringothyris 

 randalli, a species which Simpson described as possessing the 

 internal structure of Syringothyris, along with a plicated fold and 

 sinus. As is well known, Syringothyris is a Spirifer having a high 

 area, a simple fold and sinus, and the characteristic "twilled cloth" 

 sculpture. Internally there is developed a delthyrial plate, not 

 to be confounded with the deltidial plates, which bears on the inner 

 side the split tube characteristic of the genus. Typical Syringo- 

 thyris is generally regarded as being an offshoot of the ostiolate 

 Spirifers. Professor Schuchert gives the following reasons for 

 establishing the genus: 



Another phylum originated in the Atlantic realm of the Appalachian 

 province in Spirifer randalli, which also has a well-developed syrinx, but 

 differs from Syringothyris of the Mississippian sea in having a strongly plicated 

 fold and sinus. This stock must be separated generically from those of the 

 Mississippian sea because of its different phyletic derivation, and for it is 

 proposed the generic name Syringopleura (from syrinx and pleura or rib, 

 having reference to the plicated fold and sinus), with S. randalli Simpson 

 as the genotype. 



Now I am compelled to question the validity of the genus 

 Syringopleura on all the points advanced by Professor Schuchert. 



In the first place, it seems highly probable that 5. randalli does 

 not possess the external peculiarity on which the genus was chiefly 

 founded — the plicated fold and sinus. Syringothyroid shells are 

 extremely abundant at the locality and horizon at which S. randalli 

 was found, and I have examined a large number of specimens 

 without in a single instance finding any which possessed the char- 

 acteristic mesial plications. It is possible, of course, that the 



1 Published by permission of the Director of the U.S. Geological Survey. 



2 Am. Jour. Sri., XXX (ioio), 224. 



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