Clarke — The Naples Fauna. 



129 



Of the specimens which afforded the basis of the specific descriptions 

 cited, there is none which in itself conclusively demonstrates to which of these 

 two species it appertains. They are crushed and so changed as to have lost, 

 for the most part, their original ornament and to have rendered it impossible 

 to determine their specific characters with precision. It has seemed desirable, 

 however, to retain the specific name. The figures on Plate IX show the 

 nature of the protoconch and early shell, and also the size attained by the 

 conch at maturity and its strongly elliptical section. 



Localities. Bactrites acicnhon is found in the Styliola limestone on 

 Canandaigua lake. Whether the specimens found commonly in the black 

 shales of the Genesee beds, above and below the Styliola limestone and 

 referred to in the original description, belong to this species it is not now- 

 possible to say. A similar shell abounds in the soft shales of the Naples beds 

 and uncompressed specimens occur in the calcareous nodules in Erie, Ontario 

 and Livingston counties. The young shells figured are barite replacements 

 from the vicinity of Honeoye lake. 



The Phylogenic Status of Bactrites. 



We have already quoted the opinion of Professor Hyatt given in the 

 " Genesis of the Arietidae," as to the significance of this genus, and his later 

 expressions upon this point are somewhat more precise though of the same 

 intent. Before citing these opinions, we may here direct brief attention 

 to a protoconch described by the writer from the fauna of the Styliola 

 limestone. This was discussed prior * to my studies of the Early stages of 

 Bactrites and was originally referred to as the Protoconch of Orthoceras. In 

 the figures 23-25, on Plate IX, I have redrawn this body with the same degree 

 of enlargement as the illustrations of the same part in Bactrites. Comparison 

 of these figures will show considerable similarity in form but a wide differ- 

 ence, first, in actual size and, again and of primary importance, in the position 

 of the sipho. It was upon the central position of the latter in this unique 

 specimen, contrasted to its lateral position on the first septum in Bactrites 

 that I tentatively regarded this protoconch as appertaining to Orthoceras, not- 

 withstanding the evidence adduced by Professor Hyatt to show that in 

 O rthocer a s the protoconch was represented only by a wrinkled and shriveled 

 remnant. With regard to this body Hyatt, in his more recent and remarkable 

 paper, entitled the Phylogeny of an Acquired Characteristic,-!* observes that this 



* American Geologist, vol. xii, p. 112, 1893. 



t Proceedings Ainer. Philos. Society, vol. xxxii, Xo. 143. 



9 



