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. 
The shell structure is more or less distinctly and 
abundantly punctate. It is probable that these 
punctae perforate the epidermal layer and extend to 
the inner laminae of the shell. The exterior is usually pnm.yy laraeiise of 
V Syringoinyris 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, and 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 Spieifer, e. g., S. striatus, 
* Annals and Magazine of Natural Histoi'y, Fourth series, vol. ii, p. 18. 
