Geol.— Vol. I.] SMITH—PLACENTICERAS. 20I 



As to the goniatite radicle of Hoflites and of the other 

 perisphinctoids, the writer's investigations point to some 

 glyphioceran form, possibly Glyphioceras itself. Now E. 

 Haug (1898, pp. 39, 46, 73) claims that Hyatt's family, 

 Glyphioceratidee, is nothing but a group of morphological 

 equivalents from three distinct stocks or phyla, the Glyphi- 

 oceratidiE proper, the Gephyroceratidce, and the Agoniati- 

 tidee; a number of species grouped in this latter phylum 

 are classed together under the new name Pronannites, as 

 supposed ancestors of Nannites. Just this very group of 

 glyphioceran forms most nearly resembles the goniatite stage 

 of Hoflites. Haug is, then, in essential agreement with the 

 writer, although he calls these by other names. Now since 

 this classification of the goniatites, although certainly the best 

 proposed up to this time, is too arbitrary, based too little on 

 what we know, and too much on what may be so, the writer 

 prefers for the present to call the goniatite stage of Hoplites 

 gl3^phioceran, freely admitting that it may eventually be 

 referred to Pronannites, or to some other genus at present 

 insufficiently known. And should any of these stages be cor- 

 related with Nomismoceras, this genus should still, according 

 to E. Holzapfel (1899), be referred not to the Gephyrocer- 

 atidas,but to the GlyphioceratidcC, the morphogeny of which 

 group has already been described by the writer (Smith 

 1897). Noimsmoceras is probably a derivative of Glyphi- 

 oceras, for some species of Lytoceras, after passing through 

 a glyphioceran stage, show what might be called a nomis- 

 moceran stage. 



