INVERTEBRATE PALEONTOLOGY. 407 



closely in its details with the first ; second lateral lobe as long on the siphonal 

 side as the first, but broader, with two very short, digitate, terminal branches, 

 and short, nearly simple, lateral digitations; antisiphonal lobe small, nearly 

 ovate, and provided with one terminal and about three short, nearly or quite 

 simple, lateral digitations. 



Length unknown ; greater diameter at the larger end of a specimen, 

 consisting of a portion of the non-septate part, incomplete at both ends, 0.75 

 inch ; smaller diameter of same, measuring across so as to include the undu- 

 lations, 0.60 inch; same, between the undulations, 0.50 inch. 



I refer this little Baculite to B. anceps with some doubts, because the 

 specimens have the siphonal side more obtusely rounded than is generally 

 shown in the figures of European forms usually referred to that species ; 

 while the lobes and sinuses of its septa do not agree very closely in their 

 details with the published figures of those of Lamarck's species. D'Orbigny 

 seems to think that shell generally carinated on the siphonal side, as he has 

 illustrated it ; though some others refer to it forms that have that margin 

 nearly as obtuse as in our shell. Others again illustrate it as having that 

 margin narrow and prominent, but flattened on the edge; while Dr. Roemer 

 refers to it a Texas form even more obtuse on that side than any of our speci- 

 mens. 



Whether or not the true B. anceps really varies to such an extent as to 

 include all of these and other forms that have been referred to it, I am 

 unable to express any positive opinion of my own, not having had an oppor- 

 tunity to study an authentic series of European specimens of these forms. 

 If I may be permitted to judge, however, from published figures and descrip- 

 tions, I should think that shells belonging to more than one species have 

 been included under Lamarck's name. For this reason, I have not cited in 

 the synonymy several names representing forms with which I am not well 

 acquainted, but which have been by others referred to B. anceps. 



That our shell, however, is identical with the Texas form referred by 

 Dr. Roemer to B. anceps, I can scarcely entertain a doubt ; and, although it 

 has its siphonal side more obtuse than Dr. Morton's B. carinatus, it may 

 possibly be specifically identical with that shell, which agrees well with B. 

 anceps, as figured by d'Orbigny, excepting in some of the less important details 

 of the septa. Mr. Gabb has expressed the opinion that Morton's B. asper is 

 also a synonym of B. anceps; but in this opinion I am not at present pre- 



