﻿479 



The diameter of the largest specimens was estimated at 177 mm.; 

 the imperfect living chamber in this was somewhat less than one-half 

 of a volution in length. The transverse diameter of the septal floor 

 of this chamber was, estimating by half measurement, more than 

 74 mm., the ventro-dorsal about 50 mm. The siphuncle from 

 which the measures were taken may not have been in the centre in 

 this specimen, so the measurements of the transverse diameter may 

 be faulty. The living chamber in this and the next specimen de- 

 scribed reached well into the first half of the fifth volution, as esti- 

 mated by careful comparison with the young specimen above de- 

 scribed and figured. 



The most perfect fossil of this species was 140 mm. in diameter. 

 The living chamber showing lines of what appeared to be the 

 rugged edge of an aperture was just one-half of a volution in length. 

 The suture of the septal floor was similar to that described above. 

 The transverse diameter at the septal floor was about 60 mm., the 

 diameter through the side about 31 mm. The transverse diameter 

 midway in this chamber became nearly 74 mm., and the diameter 

 through the side 40 mm. 



Near the aperture the ventro-dorsal diameters continued to in- 

 crease and the transverse decreased, or in other words the aperture 

 was not so broad as the middle of the chamber which was slightly 

 expanded. The shell was enormously thick on the venter, showing 

 age, it was near the middle about 2 mm. in thickness, and near this 

 aperture 6.5 mm. in thickness. The lines of growth indicated a very 

 large, broad and deep hyponomic sinus and broad lateral crests, but 

 these were not distinctly seen. 



The siphuncle, in the specimen 177 mm. in diameter, reached 

 the large size of 1 1 mm. at the septal floor, and less than one-half of 

 a volution younger was 6.5 mm. in diameter. The septa were only 

 6 to 6.5 and 7 mm. apart as measured on the siphuncle at this age 

 near the living chamber. They were nearer together than in adults 

 at this gerontic stage as is usual in outgrown specimens. The last 

 two sutures of the smaller fossil described as 140 mm. in diameter 

 were 7 mm. distant, which is probably the average distance of a 

 full-grown shell, judging also by the remains of an isolated siphuncle 

 in the collection belonging to this species. 



LlTOCERAS BIANGULATUM, 11. S. 



Loc, Pt. Rich., Newfoundland. 



This shell appears in the collection at Ottawa under the name of 



