INVERTEBRATE PALEONTOLOGY. 



399 



One very large specimen now before me from Colorado (1 do nol know 

 the exact locality), imperfect al both ends, and aboul half its length consist- 

 ing of the septate portion, measures nearly twenty-three inches in length, 

 with its greater diameter at its larger end about 3.90 inches by nearly 3.30 

 inches, and at its smaller aboul '1. 00 inches by 1.50 inches. This specimen 

 presents nearly the same form of section, and the strong, large, lateral undu- 

 lations on its non-septate part seen in II. grandis. Yet the two terminal 

 divisions of its first lateral lobes, instead of being long and merely digitate, 

 are short and distinctly bifid ; the subdivisions being armed with sharp, pal- 

 mately spreading (limitations, more nearly as we generally see in B. ovatus, 

 with which it also agrees very nearly in the form of its antisiphonal lobe, 

 and, indeed, in the details of its other lobes and sinuses. So we here have 

 a shell agreeing in size, the form of its section, very large lateral undulations, 

 and other external characters, with B. grandis ; and yet in the characters of 

 its septa corresponding much more nearly with B. ovatus. I am not pre- 

 pared at present to decide to which of those species or varieties it should 

 lie referred, nor yet to view it as a third species distinct from both I 

 rather incline, however, to the opinion that it may lie only a very large 

 example of B. ovatus. 



Fig. 53. 



Baculites urandis (sections). 

 Fig. f>3. The ovate inner figure represents the form of a section of a medium-sized specimen, some distance 

 behind tbe last septum ; the middle line represents the form of the section of the non-septate 

 part of a large specimen, measuring between the undulations; and the outer line that of 

 same, measuring over tin- undulations farther forward. (Reproduced from the original illus- 

 tration). 



