48 PALEONTOLOGY OF NEW YORK. 



processes are given off, which are curled toward each other with some irregu- 

 larity, not meeting except where coalesced with the apical callosity, forming a 

 tube which is split along its inner surface. This tube is adherent to the trans- 

 verse plate as far as the latter extends, and is frequently produced beyond its 

 termination. 



Muscular scars as in Spirifer, their anterior portion being divided by a short 

 median septum which is an extension from the apical calcareous deposit. 



The brachial valve is spiriferoid in all internal details. The cardinal process 

 is broad, multistriate and supported by a short median thickening. The spirals 

 are large, the primary lamellae bearing a pair of short, 

 discrete spinous processes which represent the loop. y^ l). 



The shell structure is more or less distinctly and 

 abundantly punctate. It is probable that these 

 punctge perforate the epidermal layer and extend to 

 the inner laminae of the shell. The exterior is usually ^'" ^^ '^''^ pnmaiy lameiLo^ of 



•^ Syringothyris typa- 



covered with a finely textile ornament which has 

 been compared, in appearance, to " twilled cloth." 



Type, Syringothyris typa, Winchell. Burlington limestone. 



The relations of this genus to the Spirifers with smooth fold and sinus {Osti- 

 olati) have already been adverted to at some length. In view of the existence 

 of at least one punctated species of Spirifer {S. plenus, Hall) in which the trans- 

 verse plate and split tube of Syringothyris are not present, aiid of gradational 

 conditions in respect to other points of structure, which have been noticed, it 

 is quite safe to assume that this peculiar group of forms is an outcome from 

 normal development with variation along that spiriferoid line. The extrava- 

 gant structure within the delthyrium, termed the split tube, may be regarded 

 as the extreme manifestation of a tendency in all the later spiriferoids with 

 plicated exterior to excessive secretion of testaceous matter in this region. 

 Dr. King, in 1868,* claimed to have found traces of this tube or canaliferous 

 plate in a rudimentary condition in several species of Spirifer, e. g., S. striatus, 



* Annals and Magazine of Natural Histoiy, Fourth series, vol. ii, p. 18. 



