Weller — Kinderhook Faunal Studies. 45 



CEPHALOPODA. 



Orthoceras chemungense Swallow. 



PL V. f. 16. 



"Shell small, tapering moderately; transverse section 

 elliptical; septa very concave; distant nearly half the shorter 

 diameter; siphuncle small, central." 



" Longest diameter, .64 ; shorter diameter, .51 ; distance of 

 septa, .24; diameter of siphuncle, .06." 



Bemai'ks. This species was originally described from the 

 Lithographic Limestone of Marion and Pike Counties, Mis- 

 souri, and the original description is copied above in full. 

 Since the sutures are rarely recognizable in the Northview 

 specimens it is probable that most of them are fragments of 

 the living-chamber, which was apparently rather long. The 

 specimens agree closely with Swallow's description. The pro- 

 portions of long diameter, short diameter and distance of 

 septa in the best preserved specimen are 65-52^-26, as 

 against 64-51-24 as given by Swallow. The largest shell 

 among the Northview fragments has a long diameter of 24 

 mm., which is perhaps greater than any of Swallow's speci- 

 mens although he makes no statement in the description 

 further than that the shell is small. Upon the better pre- 

 served specimens very fine lines of growth may be recognized, 

 though in general the specimens are smooth, and in one frag- 

 ment the shell shows a moderate constriction so it is possible 

 that the shell was somewhat constricted near the aperture. 

 In no specimen has the position of the siphuncle been 

 observed. 



Triboloceras digonum (M. &W.)? 



Fl. V.f. 17-18. 



This species is only known from fragmentary specimens, 

 all of which are apparently portions of casts of the living- 

 chamber, as in no case have the sutures been observed. The 

 form and ornamentation of the shell, however, show that it 

 is a member of this genus, and that it approaches very close 

 to or is identical with T. digonum. 



