SUPPLEMENT. 317 



Oraptolithus spinulosus ( n. s.). 



Stipe simple, flat ; sides subparallel, gradually expanding from the base, 

 which is furnished with several minute setiform radicles : serraturea 

 not distinct, the margin sinuous, the prominent parts extended into 

 slender ascending spinuliform processes. These spinules are about one- 

 sixteenth of an inch distant from each other. 



This species presents no distinct serratures on the margin, which is simply un- 

 dulating with the extension of the processes described, which probably mark the 

 place of the serrature. It has been seen only in small individuals or fragments; 

 but its great comparative width, the rigid distant spi- 

 nules and absence of defined serratures are distinguish- 

 ing characters. 



The accompanying figure is of a fragment of this 

 species, twice the natural size. 



Geological position and locality. In the shales of the 

 Hudson-river group : Near Albany. 



The Genus Gladiolites or Retiolites of Barrande was proposed for 

 certain graptolitic forms having the general features of the biserrate 

 Graptolites, as G. pristis, G. mucronatus, and others ; but the structure of 

 the entire substance of the stipe diflfers in being apparently minutely 

 celluliferous or reticulate. 



The following is the description given by the author : 



GExrs Oladiolites = Retiolites (Barrande). 



" PoLTPiER small, flat, triangular, elongate, formed of two series of sym- 

 metrical cellules arranged along the axis. These cellules extend from a 

 single internal canal, which occupies the central part of the polypier : 

 their orifices are disposed upon the sides of the triangle ; they make an 

 angle with the axis, and leave no spaces between them." 



" The only known species has its surface covered with a film, which appears to 

 envelope it." 



