120 PALAEONTOLOGY. 



Zoology. I will take this opportunity, however, to say that there were 

 peculiarities in my attempt to frame a new classification for the Ammonites 

 which have passed unnoticed. The species were .an-anged in series whose affin- 

 ities and genetic connections were successively traced, just as any zoologist 

 would trace the same relations among any disorderly mass of animals. The 

 usual paUieontological style of making genera, as if families and larger groups 

 had no 'raison d'etre', and the genera themselves no interdependent affin- 

 ities, was carefully avoided. Another peculiarity was that two of my much 

 abused genera precisely agreed with two of those so well described in the 

 justly-admired work of Professor Suess; and as the thirty others described 

 independently by me were founded upon precisely the same set of differ- 

 ences, I find myself unable to appreciate criticisms which 'blow hot and 

 cold' upon the same subject, according to the man, and not the man's 



work."— (A. II.) 



Arckstes? perplanus, ]\Ieek. 



Plate 11, figs. 7 andTi. 



Shell strongly compressed, or nearly flattened-subdiscoidal, the lateral 

 compression making the periphery so narrow as to appear almost subangu- 

 lar; umbilicvis very shallow, and equaling about one-fourth the gi-eatest 

 diameter of the shell; volutions five or more, nearly flat on each side, increas- 

 ing gradually in size, and each enveloping about two-thirds of the next 

 within; aperture, as determined from a section of the whorls, very narrow 

 at right angles to the plane of the shell, and profoundly sinuous on the inner 

 side for the reception of the next turn within. Surface without nodes, 

 costse, or (on casts) visible remains of striae. (Septa unknown.) 



Greatest diameter of the largest specimen seen, 2 inches; convexity of 

 same, 0.30 inch. 



This species is chiefly distinguished by its remarkably compressed form. 

 The only two specimens of it seen are also very slightly elliptical in outline. 

 This latter character, however, may be due to accidental distortion ; but as 

 a similar in-egularity of form exists in a number of specimens of another 

 associated shell, and the same want of symmetry has been noticed by Pro- 

 fessor Hauer in species from rocks of the same age in the Alps, and by Dr. 

 Stohczka in the Himalaya Mountains, under cu-cumstances leading to the 



