276 



same rocks by Orthoceras sericceum. It has been thougbt 

 remarkable tbat tbe less simple forms sbould precede the 

 straight orthoceras ; but the history of discovery shows that we 

 canplace but little trust in such an isolated fact as it is liable any 

 day to be reversed.'^* Although, therefore, we might be able 

 to claim for the cyrtoceras the distinction of being the primal 

 cephalopod, and so show the impossibility of its having, as the 

 President thought, descended from orthoceras, yet we decline 

 to snap a verdict in this manner, lest it should be reversed on 

 a new trial by the production of further evidence. We prefer 

 to open the question and look at all possible evidence in 

 support of the Professor^s proposition. 



Those who have to plead for evolution from the orthoceras 

 do not affirm that this was the first creature of its kind, but 

 the first creature of present kinds. They assume the existence 

 of some earlier stage of life (of which, however, we have no 

 evidence whatet;er), in which there existed earlier and simpler 

 creatures whence either cyrtoceras or orthoceras proceeded, or 

 both. Palaeontologists know nothing of this. Mr, Hyatt admits 

 that " in all the larger series of shell-bearing cephalopods the 

 nautiloid shells belong to several distinct series/^ which, he 

 states, " arose independently from straight cones through the 

 intermediate graded series of arcuate and gyroceran or clearly 

 coiled forms. ^^ He lays it down that the ammonites are evi- 

 dently descendants of the nautilinidge, and that the evidence 

 is strong that the whole order arose from a single organic 

 centre, the nautilus of the Silurian, or the orthoceras of the 

 Cambrian. But how is this statement consistent with the 

 conclusion of the same writer,t that the study of the tetra- 

 branchs teaches us that, '' when we first meet with reliable 

 records of their existence, they are already a highly organised 

 and very varied type, with many genera." They must have 

 had ancestors now unknown to us, " but at present the search 

 for the ancestral form is, nevertheless, not hopeful.'^ 



When you visit the grand, capacious Natural History Museum 

 at South Kensington, you find, in the department devoted to 

 molluscan fossil remains, one room, — the first, — appropriated 

 to cephalopods. The first cases on the right, as you enter, con- 

 tain the orthoceratites, and next to these are the cyrtocera- 

 tites. This relative position is not indicative of order in time, 

 but of apparent simplicity of form. The distinction between 

 the two forms is immediately perceived. The cephalopod 

 room is well worthy of study in the light of the eai-ly appear- 

 ance of these creatures on the earth, and their apparently 



* Blake, Britiah Cephalopoda, p. 238. t Science, Feb. 1, p. 127. 



