CANADIAN FOSSILS. 67 



This species presents some variations in form and size. The 

 greater number of the specimens are nearly globular, and about one 

 inch in diameter. Fig. le, plate vii. represents an individual that is 

 ovate, the length being fifteen lines and the breadth twelve lines. 

 Fragments have been observed which must have belonged to speci- 

 mens two inches in diameter. The plates are also sometimes 

 exceedingly convex, the sutures being depressed. In specimens 

 with smooth surfaces, or with the plates not convex, it is almost 

 impossible to distinguish the sutures. 



Dedicated to Sir Roderick I. Murchison, F R.S., Gr.S., &c. &c. 

 Director-General of the Geological Survey of the United Kingdom 

 of Great Britain and Ireland ; author of "The Silurian System," etc. 



Explanation of Figures. Plate VII. 



Fig. la. Right side of a specimen, shewing the ambulacral orifice and the eight arms. 

 lb. The left side, shewing the position of the mouth, m. le. Vertical yiew 

 of the ambulacral orifice. Id, le, Left sides of two other specimens. 

 If. Apex of le. Ih. Base of la!, shewing the three basal plates, li. Portion 

 of upper surface of an arm magnified. 



Locality and Formation. — Chazy limestone, Caughnawaga and 

 Island of Montreal. Fragments are exceedingly abundant; good 

 specimens rather uncommon. 



Collector. — E. Billings. 



XV. Maloctstites Baerandi, Billings. 



Plate VII. Figs. 2a— 2c. 



Description. — Ih this species the body is nearly globular, and the 

 plates smooth, or very minutely granulated with small tubercles. 

 The mouth is five-sided, and situated almost exactly in the centre of 

 the apex or diametrically opposite the point of the attachment of the 

 column. The arms are two in number, and very short, each being 

 not more than three or four lines in length. They are so disposed 

 as to form two half-circles, with the inner curves facing in opposite 

 directions. They are connected by the usual ambulacral groove, in 

 the bottom of which is the orifice. There are eight joints in the 

 arm preserved in the specimen fig. 26, pi. vii. which is the posterior 

 arm, or that most distant from the mouth. The specimen repre- 

 sented by fig. 2c has the anterior arm preserved, and it shews only 

 four joints. 



