GS BULLETIN OF THE 



especially Baculites, have young which are straight or closely coiled, I 

 could not ascertain hy direct observation. 



The ovisac of Goniatites does not, in the majority of the species, 

 differ very materially from that of Ammonites. It is evidently an 

 elliptic or globose body more or less flattened on the abdominal side as 

 in the typical Ammonites* It however presents very remarkable 

 differences in the relations of the ovisac to the first whorl and to the 

 umbilicus, and in its variability of form in the same -and different 

 species. 



Dr. Guido Sandberger figured several species, all of which are re- 

 produced in the first Plate of this paper,f and from these and others, 

 also examined but not figured, he inferred that the species themselves 

 might be distinguished by the differences of the embryos. The 

 figures certainly appear to justify this remark, and my own observa- 

 tions, as well as those of Barrande, though apparently contradictory, 

 are really strongly confirmatory. Barrande found in the silurian of 

 Bohemia Goniatites fecundus, and Goniatites plebius with two well- 

 marked varieties, and was so fortunate as to obtain also the very 

 youngest stages of growth in each variety of the former, j These are 

 also reproduced on Plate I of this work.§ According to Barrande 

 the ellipticity of the orbit in the adult of one variety is due to the 

 straightness of the first portion of the first whorl, and the regular 

 spiral of the other variety to the close coiling of the young. He also 

 observed and figured the same elliptical form at all stages of growth. 

 This would seem to be sufficient to establish the two varieties as dis- 

 tinct species ; but the presence of all intermediate varieties between 

 the two produced here, the similarities of the adult shells, and the 

 occurrence of the same variations in Goniatites plebius forbids their 

 separation. 



Goniates crenistria, in one so-called variety, has a decidedly rounded 

 abdomen, and the ovisac fills the fundus of the umbilicus, while in the 



* Plate III, Figs. 3 4. 



f'Diese ist stets stark aufgebliiht und wie die Figuren 26 bis 33 (PI. I, Figs. 11- 

 18) beweisen, bei don verschiedenen Arten oft von sehr characteristischer Gestalt, so das 

 sie in manchen Fallen ein zur Unterscheidung der Species geeignetes Merkmal abgiebf." 

 — Guido Sandberger, Beob. Uber Gonialilen, Jahrbuch der Nassau Verein, 1851. 



J Syst. Sil. de BohGme. Cephalopods. Vol. II, pp. 32 and 37. Plates 7, 10, 11, 17 

 and 5, G, 7,241, 242. 



§ Plate I, Figs. 9, 10. 



