Riedemaxx— Sessile ( Jontjlabia. 



719 



The marginal grooves and pyramidal shape would appeal- to be of secondary 

 acquisition. 



Bearing in mind these supposed characters of the ancestors of Con ulwid, 

 the suggestion of A. E. Verrill in the above-mentioned paper that Conularia 

 represents a very primitive genus belonging to the Cephalopods appears quite 

 reasonable. The Pterqpods, to which Conularia has been so long referred, 

 are claimed by zoologists to be a very late class, while the Cephalopods are 

 recognized among the fossils of the Cambrian and were, probably, at the 

 beginning only sluggish or even sessile animals which acquired the power of 

 fast motion later. The Glutinous material of the shell of Conularia seems to 

 the writer, to be no ground for objection, for there still exists to-day a group 

 of Cephalopods with chitinous shells, viz. : the Chondrophora of P. Fischer. 

 Further, the suggestion made in regard to other classes of shell-bearing 

 animals, that chitine was probably the original shell-material which has been 

 replaced later by other materials, probably holds also true for the < ' [>hal.<>p<><h. 

 There are a few observations which point to this supposition. Hyatt" and 

 Holmf observe that the protoeonch of Endoceras (Nanno) belewmiUforfne and 

 of other Nautiloidea is represented by a cicatrix only and hence was fragile 

 and easily destructible. Hyatt concludes from this observation that the 

 protoeonch of some Nautiloids was chitinous; others, as shown by Clarke,! 

 possessed already a calcified protoeonch. 



The occurrence of septa in certain species of Comilaria,§ though of no 

 great significance, indicates at least, that the animal advanced in the shell. 

 The Cephalopods r did the same, but in a manner which proves their higher 

 development also in this regard. 



If the genus Conularia indeed represents a group of transitional forms, 

 it would seem appropriate to recall the fact that progress from slower to 

 faster swimming was attained among certain Cephalopoda (the Belemnites) by 

 reducing and enclosing the shell, and to consider the possibilitv that the 

 Conularia did not become extinct, but taking part in the general progress of 

 the class, developed into Cephalopoda with an internal shell and became thus 

 less liable to be preserved in a fossilized state. 



Referring to this possibility, it should be borne in mind that the above- 

 mentioned Chondrophora, which are characterized by a chitinous gladius, have 

 not yet been linked phylogenetically to any group of the fossil Cephalopods, 



* Genesis of the Arietidae, 1889. 



+ Geologisk Fiirenings Fiirhandlinger. Vol. XVII. 1895. 



t American Geologist, Vol. XIV. October. 1891, p. 205. pi VI. 



§ As many as three septa have been observed in the same specimen (cf. A. Ulri'-h, Paheozoische Versteinerungen aus Bolivien, 

 1892, p. 32. 



