Geology and Mineralogy. 463 



Some conclusions resulting from the work recorded in this Bul- 

 letin are set forth by Professor Williams in another paper entitled 

 " Bearing of some new paleontologic facts on nomenclature and 

 classification of sedimentary formations " (Geol. Soc. Amer., 1905). 

 His conclusions are at variance with the experience of other 

 paleontologists, a fact clearly brought out in a recent discus- 

 sion by the paleontologists of the IT. S. Geological Survey (Stan- 

 ton, Dall, Ulrich, and White) and summarized in Science, April 

 14, 1905 (pp. 583-585). CHARLES schuchert. 



3. Structure of some Primitive Cephalopods y by R. Ruede- 

 mann. Rept. N. Y. State Pal., 1903 (April, 1905), pp. 296-341, 

 pis. 6-13. — This very important and highly instructive paper 

 treats in the main of the structure and development of JEndoceras 

 brainerdi of the lowest Ordovicic of the Lake Champlain region. 

 It is shown that this primitive cephalopod begins with a proto- 

 conch followed by a long, gradually tapering, rather large and 

 non-septate cone, as in Nanno and Vaginoceras. After attaining 

 a length of about *10 mm , a slight constriction of the cone takes 

 place and at this point it may be said that the wall of the cone 

 divides, the inner division (or conchiolinous portion) to continue 

 as the wall of the siphuncle (a continuation of the original cone 

 cavity), while between it and the outer calcareous wall is devel- 

 oped the camerated space, or phragmocone. Within the siphun- 

 cle, after a few of the camera? have been developed, there then 

 appear other cones, the endocones, which communicate with one 

 another by means of a central canal, or " endosiphuncular canal." 

 The wall of the siphuncle rests against the recumbent edges of 

 the cameras walls until within a few inches of the terminal 

 growth, where the cameras (or " septal necks ") form the lining to 

 the large siphuncle opening directly into the living chamber. 

 There are further siphuncular complicating structures about the 

 endosiphuncular canal too complicated to be given here in a few 

 words. However, it should be added that these developments led 

 the author to a comparison of these structures with the Belem- 

 nites, and he concludes that the " endosiphocoleon " of endoce- 

 roids and the proostracum in the Belemnites are " formed in iden- 

 tical places," i. e., " within a mantle flap or fold situated at the 

 posterior end of the animal." 



The author then discusses various early endoceran genera and 

 concludes that the genera -Cameroceras (syn. Endoceras) and 

 Vaginoceras have earlier generic types for which he proposes 

 Proterocameroceras and Proterovaginoceras. The latter is con- 

 sidered to contain the radical stock for these primitive forms. 

 As Piloceras is closely related to these genera, the author also 

 studied the development of this genus in P. explanator. From 

 a study of this form he concludes that there is also here an earlier 

 type with an external primitive cone, as in Proterocameroceras. 

 To this very interesting but as yet undiscovered form, he gives 

 the generic name Proteropiloceras, which of course no one is 

 obliged to accept, under the rules of nomenclature. Piloceras 



