406 NEW YORK STATE MUSEUM 



Cameroceras (Proterocameroceras) brainerdi, Rue- 

 demanii. An. Rep't State Paleontol. for 1903; N. Y. State Mus. Bui. 80. 

 1905. p. 296ff 



The attention of Professor van Ingen and the writer was, at 

 the time of their collecting in the Fort Cassin beds at Valcour, at 

 once attracted to large, very gradually tapering orthoceratites 

 which frequently attained a length of a foot and a half or more 

 and were piled up in mud channel fillings of the Beekmantown 

 rock, together with Ophiletas and other gastropods. Comparison 

 with the original description and types, and with material from 

 Fort Cassin in the State Museum has demonstrated the identity of 

 these shells with Orthoceras brainerdi, a species described 

 by Whitfield from the original Fort Cassin beds. To the careful 

 description of the septa, sutures, position and size of the siphuncle 

 by the author of the species, we have little to add. Our material 

 from Valcour and specimens from Fort Cassin have however al- 

 lowed us to make out the endosiphonal structures and the char- 

 acters of the apical end, both of which proved to be of great interest 

 and have been made the object of a separate investigation since 

 they invited a fuller discussion.^ 



Description. Orthoceracones of large size ; specimens measured 

 had attained a length of i^ feet (45cm) with the greater part of 

 the apical portion missing, and hence must have reached at least 4 

 feet and probably considerably more. The conch expanded very 

 gradually, the rate of growth being about 1 130 (15 mm in 450 mm). 

 Diameters of 60 mm in the septate portion have been observed. 

 The section is elliptic, the ratio of the major and minor diameters 

 as 7 : 9. 



Surface smooth and only provided with growth lines. 



The living chamber was apparently of moderate size and lacking 

 apertural contractions. In a specimen having a diameter of more 

 than 50 mm at the base of the living chamber it has a length of 

 135 mm or not quite three times the width of its base. Its surface 

 was marked with faint transverse lines (growth lines). 



Cameras shallow, their depth about one fifth the width ; septa 

 closely arranged, 3 to 4 mm distant from each other (7 in the space 

 of one inch or of 25 mm in the mature parts of the conch) each 

 running up along the outer shell to the base of the succeeding sep- 

 ■;um ; sutures undulating, showing a narrow, often acute siphuncular 



1 State Paleontol. An. Rep't for 1903. N. Y. State Mus. Bui. 80. 1905. 

 p. 296ff. 



