CANADIAN FOSSILS. 53 



from the base of the body to the upper angle of the large dorsal 

 hexagonal plate, and the right half of the left upper rhomb is in 

 length five lines and in breadth one line. The plates appear to have 

 been smooth, and in this respect principally does the species difier 

 from P.Jilitextus, which is much ornamented with radiating striEe. 

 This is the only species we have as yet from the Hudson Eiver group. 



Explanation of Figure. Plate I. 

 Figure 3. Dorsal view of an imperfect specimen of this species. 



Locality and Formation. — Charleton Point, Island of Anticosti ; 

 Hudson River group. ^ 



Collector. — J. Richardson. 



Genus GtLtptocystites, Billings. 



{Canadian Journal, vol. ii. p. 215, 1854; Geol. Survey of Canada, Report, 1856, p. 280.) 



Generic Characters. — Body, elongate, cylindrical ; test composed 

 of four series of plates, of which there are four in the basal, and 

 five in each of the second, third and fourth series ; three of the basal 

 plates are pentagonal, the fourth hexagonal ; the mouth, in the only 

 species in which it has been seen, is situated in the lower half of the 

 body, its lower side being formed of a notch in that plate of the 

 second series which rests upon the hexagonal basal plate ; it is 

 without a valvular apparatus ; the ambulacral orifice is in or near 

 the centre of the summit, where it receives the five ambulacral 

 grooves of the arms ; near it is a small anal ? pore ; there are from 

 ten to thirteen pectinated rhombs ; the arms are recumbent, and 

 upon the apex of the fossil the ambulacral grooves are beset with 

 small marginal plates; the pinnulae are articulated in two series; 

 the column is short, and tapering to a point at the lower extremity. 



The plates of the cup of this genus are somewhat remarkable for 

 their form. In the hitherto known Crinoideae and Cystidege they 

 are polygonal and bounded by straight sides ; but all the species of 

 this genus yet observed have some of them with re-entering angles. 

 By referring to pi. iii. fig. la, it will be seen that the basal series of 

 G. muUiporus is very regular, and exactly like that of the genus 

 Echino-encrinites (Volborth), represented in fig. lb, the only difference 

 being that the dorsal plate is so much extended upwards as to 

 separate two of the plates of the second series. These two plates 

 are notched on the upper side for the reception of the small 

 hexagonal plate of the third series. Several of the other plates are 



