Fossils of the Chazij Limestone. 461 



centre of the trausverse section half its own diameter. Surface 

 unknown. 



In a specimen eight inches long the diameter of the larger 

 extremity is ten lines and of the smaller five lines, and it tapers 

 therefore at the rate of five eighths of a line to the inch. At the 

 larger end there are two septa in nine lines, and at the smaller 

 two in four lines. The siphuncle is cylindrical and but slightly 

 inflated between the septa ; its diameter at its passage through the 

 septum at the large end one line and a half, and between the 

 septa about two lines. 



We have no species with which this Orthoceratite can be com- 

 pared except 0. amplicameratum (Hall), from which it differs in 

 having the septa proportionally a little more distant, and the 

 siphuncle a little larger and not so excentric. 



Dedicated to the excellent geologist and palaeontologist, Dr. B. 

 F. Sbdmard, State Geologist of Texas. 



Locality end Formation. — Mingan Islands; Chazy. 



Collectors. — Sir W. E. Logan, J. Richardson. 



Ortiioceras Maro, N. sp. 



Description. — Annulated, slightly curved, section circular, taper- 

 ing at the rate of one line and a half to the inch ; siphuncle about 

 one eighth the whole diameter, and with its centre half its own 

 diameter from the centre of the shell ; septa rather strongly con- 

 cave, two in five and a half lines where the shell is one inch in 

 diameter, three in live lines where it is half an inch in diameter. 



The annulations in general encircle the shell at right angles to 

 the length, but in some of the specimens they appear to be gently 

 sinuated on one side. They are rather abruptly elevated with 

 rounded edges, and the spaces between them are either regularly 

 concave or nearly flat for about one fourth or one third their 

 width in the middle or at that part of the bottom of the space 

 which is situated half way between the annulations. The thick- 

 ness of the rounded edge of the annulations is about half a line 

 and the height of the ridge about one line. Where the diameter 

 is one inch the annulations arc distant three lines, and where it is 

 half an inch they are distant one line and a half. 



The surface is ornamented with line longitudinal stria', about 

 ten in the width of one line. These striae are in some places 

 alternately a little unequal in size, and they also appear to be 

 crossed by minute transverse striae, but this character has not been 



