202 . 



{Lytoceratidce.') 



Lytoceras Batesi, Trask. (Sp.) 



Plate 27, fig. 1. 



Ammonites Batesii, Trask. —1855. Proceedings of the California 



Academy of Sciences, p. 40. 

 " " Gabb. — 1864. Geological Survey of California 



Palaeontology, Vol. I., p. 67, pi. 13, 

 figs. 16 and 16a-6. 

 " '• Gabb. —1869. Idem., Vol. IL, p. 132, pi. 20, fig. 



9a, and pi. 21, fig. lOa-6. 

 Am.monites crenocostatus, Wliiteaves. — This volume, p. 45, pi. 9, figs. 2 and 2a. 



Bear Skin Bay, Skidegate Inlet : a well preserved but somewhat im- 

 perfect specimen, whose maximum diameter is four inches and three- 

 quarters. 



A re-examination of the small Ammonite to which the provisional 

 name of ^. crenocostatus was given on page 45 of the present volume and 

 which was there stated to be " perhaps a half-grown specimen of 

 Jjytoceras Liehigi, Oppel," has convinced the writer that it is only 

 a youug specimen of the Ammonites Batesi of Trask, in a somewhat 

 peculiar state of preservation. Tlie sculpture of A. Batesi, which is 

 a very typical species of Lytoceras, is thus described by Mr. Gabb on 

 page 67 of the first volume of the "Palaeontology of California." 

 " Surface marked by numerous fine, rather sharp, elevated ribs, cross- 

 ing fj'om the interior of the umbilicus obliquely forwards over the dor- 

 sum. In some specimens the interspaces are marked hj fine revolving 

 lines. In others these lines are absent." 



The sculpture of the type of J., crenocostatus, upon which the species 

 was mainly based, at first sight appears to consist of rather distant, 

 minutely crenate, transverse raised lines, placed upon the convex 

 surface of the shell, Init upon closer examination it is found that these 

 crenulations are caused by minute and underlying revolving striae, 

 which can only be seen in a certain light. 



According to Mr. Gabb,* A. Batesi is "the largest known, most 

 widely difiused, and one of the most variable Ammonites " of the 

 Shasta Group; or "older beds" of the Cretaceous formation in California, 

 where it attains to a size of more thau a foot in diameter. The same 

 species seems to have also attained to a considerable size at the Queen 

 Charlotte Islands, for in a septate fragment collected by Mr. Eichard- 

 son in 18*72 at Skidegate Inlet, west of Alliford Bay, which cannot be 

 distinguished from A. Batesi, the height of tlie apei-ture alone is fully 



♦ Palaeontology of California. Vol. II., p. 132. 



