76 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



I have been unable to discover strise of any kind, but the angular 

 annulations between the septa are characteristic. The largest dia- 

 meter of this specimen is one inch, and this length includes six 

 annulations. 



Geological formation and locality. In the Scholiarie grit at Schoharie. 



ORTHOCERAS MULTICINCTUM ( n. s.). /)( • ^ ^ 

 Shell cylindrical, very gradually enlarging from the apex : septa 



numerous; siphuncle small, central. 

 Surface annulated by numerous narrow ridges, the spaces between 



which are equal to once and a half or twice the diameter of the 



annulations : remains of longitudinal striae are preserved on a 



part of the surface. 



A specimen somewhat compressed, but which has had a diameter 

 of about three-fourths of an inch, has thirteen annulations in the 

 length of an inch; and at an inch nearer the apex, has fifteen an- 

 nulations in the length of an inch. In the same specimen, however, 

 the length of an inch from the aperture embraces only eight annu- 

 lations. In a specimen measuring three-eighths of an inch in dia- 

 meter, there are fifteen annulations in the length of half an inch. 



From this great variation in the distance of the annulations, it might 

 appear that this form is only a variety of O. thoas; but in numerous speci- 

 mens of that species, having a diameter only one quarter greater than the 

 largest individual of this species, the annulations show only the variation 

 noted in the description, and I am therefore induced to regard them as 

 distinct species. 



Geological formation aiid locality. In the Schoharie grit : Schoharie. 



/ 



ORTHOCERAS PROFUNDUM ( U.S.). 7^, ? 



Shell cylindrical, gradually tapering from the aperture : outer 

 chamber very deep ; siphuncle apparently a little excentric. 



Surface longitudinally marked by sharp ridges, which, in specimens 

 of one inch to one inch and a half in diameter, are distant about 

 one-tenth of an inch, and annulated by sharp, rather distant 

 strise, giving to the longitudinal ridges an undulated or crenulate 

 aspect. The spaces between the transverse strise are about one 

 quarter as great as between the longitudinal strise, but often show 

 finer strise of growth, and sometimes the sharper annulating strise 

 are not conspicuous. 



[ September, 



