SCAPHITES. 261 



respects presents the characters of Perisphinctes ; then to this 

 form Olc. Slanleyi, Opp. and Groteanus, Opp., from India, are 

 allied, the last of which is also found in Stramberg as the oldest 

 representative of its genus in Europe ; and this form stands so 

 near Olc. astierianus that it was at first directly identified with 

 it by Pictet. The forms allied then to Olc. astierianus, from 

 the European Neocomian, are to be placed here. 



To Olc. astierianus, the group Olc. bidichotomus, Leym. is 

 very nearly related, which, however, does not seem to have come 

 to us from India, but from the boreal regions, where Olc. dipty- 

 chus, Ke}^s., and polyptychus, Keys., from Petschora, form the 

 starting point. The close affinity between the Indian and 

 Russian cephalopodous faunae is well known, and apparently the 

 group of Olc. bidichotomus forms a boreal series parallel with 

 that of the Indo-Mediterranean of Olc. astierianus ; the appear 

 ance of the first group in Europe took place decidedly earlier 

 than that of the latter, and indeed synchronously with that of 

 the Amalthsea and Belemnites of the group Bel. subquadratus. 

 The duration of Olcostephanus in Europe is very short, they do 

 not seem to extend beyond the Neocomian, whilst they persist 

 in India for a long time in the form of flat types, with wide 

 umbilicus. . 



The character of Olcostephanus in contrast with Perisphinctes, 

 consists in a shorter body-chamber, embracing only about two- 

 thirds of a whorl, with a simpler aperture, bordered with a 

 smooth margin ; the presence of ears has been observed only in 

 Olc. Cautleyi, which stands on the limits of both the above 

 genera. Constrictions directed forward in the group Olc. as- 

 tierianus, very strong, wanting as a rule, in that of Olc. bidicho- 

 tomus. Lobular line, as a rule, consisting of a siphonal, two 

 lateral, and three auxiliary lobes, the last of which sometimes 

 are somewhat dependent. External side without keel or furrow, 

 only in a very few are the ribs there interrupted. 



Thirty-three species. 

 OLCOSTEPHANUS BHAWANI, Stol. T. Ill, figs. 658, 659. 



Genus SCAPHITES, Parkinson. 



The Scaphites, with the exclusion of Sc. Yvanii, form a very 

 good natural group, very distinctly characterized by the involute 



