44° 



NEW YORK STATE MUSEUM 



It is evident that Hall wrote his brief description mainly from 

 the anterior fragment while the draftsman extended the surface and 

 septal characters of the posterior smaller fragment to the whole speci- 

 men. As a result of these different viewpoints the description and 

 figure disagree. 



Only the anterior annulated fragment can be regarded as the type, 

 the other fragment belonging to Loxoceras monilif or m e . 

 To increase the troubles of this species S. A. Miller in 1877 

 pointed out that Hall's name was preoccupied and substituted in 

 its place the rather undesirable name Orthoceras clintoni, 

 which however has to stand. 



Hall describes the species as follows : 



Cylindrical gradually tapering, slightly arcuated, marked by 

 angular ridges which are equidistant and alternating with the septa ; 

 surface of shell smooth?; septa distant from one fourth to one fifth 

 the diameter; siphuncle not visible. 



As position and locality are given the " central dark limestone, 

 associated with Maclurea magna at Chazy, Clinton co." 



Billings records the form from the Chazy on the island of Mon- 

 treal and near Cornwall, adding " the surface characters are not 

 well known, but one of the specimens exhibits the siphuncle which 

 is strongly moniliform, and situated halfway between the center 

 and the outside. All the specimens that I have seen are curved ". 



From our own material we are able to give the following addi- 

 tional data : 



The size attained by this species in the Champlain basin has been 

 considerable. We have obtained at Yalcour (B 3 ) an incomplete 

 specimen which has a length of 57 cm and a greatest width of 

 75 mm. Its living chamber is 22 cm long. The aperture of 

 this specimen is straight. The curvature is irregular and the initial 

 fourth is as a whole curved more strongly than the later portions of 

 the shell and often bends somewhat abruptly in one place, the pre- 

 ceding and following portions of the conch being less curved. In 

 the large specimen mentioned above the arc attains a hight of not 

 moie than 10 mm. The rate of growth of the conch is small, but 

 increasing gradually. Where the width of the conch is 15 mm, it is 

 only 1 :20 ; where the conch has expanded to 36 mm it is as 1 \y. The 

 surface sculpture is also variable; the apical portion bears nothing 

 but sharp longitudinal striae as in most other annulated forms. 1 



1 We have not observed any specimen with the transition from the .non- 

 annnlated longitudinal sculpture to the annulated but the fact that near Little 

 Monty bay where S. clintoni occurs very freely and is the only annulated 



