BEEKMANTOWN AND CHAZY FORMATIONS OF CHAM PLAIN BASIN 417 



Later on, Hall and Beecher 1 had occasion to observe the filling of 

 chambers by organic deposit in several species of Orthoceras from 

 the Schoharie grit. They, in following the suggestion that the shells 

 of Orthoceras and other related genera were probably carried in a 

 vertical position, concluded that " the volume of the septate or cham- 

 bered portion being considerably in excess of the chamber of habita- 

 tion, and the external shell comparatively thin, a deposit on the 

 interior of the chambers would afford the required strength and 

 gravity ". 



Two years ago Jaekel 2 advanced a number of very suggestive 

 theses on the mode of existence of the cephalopods. One of these 

 holds that the orthoceratites were sessile in such a fashion that their 

 chambered shell grew upward from a bell-shaped fixed embryo 

 chamber and throughout life retained flexible connection with this 

 by means of conchioline secretion. In a translation of a part of 

 Jaekel's paper by the present writer 3 the ground was taken that the 

 orthoceratites probably allowed themselves to sink or actively buried 

 themselves in the bottom deposits. Among other arguments in sup- 

 port of this view the complete filling of the chambers of the Scho- 

 harie grit species cited above was named. Certain facts ascertained 

 in regard to V. o p p 1 e t u m and Endoceras? h u d s o n i 

 [see p. 422] would seem to support our contention ; i. e. that there 

 exists a difference in the amount of deposition of organic carbonate 

 of lime in different localities, and that the deposition is heaviest 

 where the irregular sedimentation and the presence of large masses 

 of coralloid forms indicate coral reef conditions but is more or less 

 absent where the presence of more regularly bedded, argillaceous 

 calcareous shale points to deposition in deeper and less turbulent 

 water. This mode of occurrence and that of the Schoharie forms 

 lead to the inference that the deposition in the siphuncle and 

 chambers served principally as a safeguard for the fragile conchs 

 against destruction by being thrown against the reefs and as a 

 device to safely anchor the shell to the bottom. This view is also 

 supported by the observation that the younger shells, which harbored 

 the younger and more active animals have only the large siphuncles 

 filled with endosiphosheaths which were sufficient to weigh down 

 the shell, that older conchs however are liable to have also the 



1 Pal. N. Y. 1879. v. 5, pt. 2, text, p. 247ft. 

 2 Zeitschr. d. Deutsch. Geol. Gesell, 1902. 54:67-101. 

 3 Am. Geol. 1903. 31:199. 



