L92 K. M. Kindle — Stratigra/phic Relations of the 



according to Forbes, numbers about 500 species, reduced in 

 the vicinity of La Spezia, with increase of the depth of the 

 water amounting to no more than 120 feet, to one or two 

 species. Jeffries's account of the rapid disappearance seaward 

 of the rich molluscan fauna of La Spezia is very similar to that 

 which the paleontologist must give of the faunal changes which 

 he encounters in passing westward from Ashtabula County, 

 Ohio. There the rich molluscan fauna of the Chagrin shale 

 in the Jefferson region is represented in every section by 

 thousands of shells belonging to many species and genera. Thirty 

 miles west of Ashtabula County the same gray Chagrin shale 

 of the Cuyahoga River valley holds a comparatively sparse 

 fauna. Still farther west, 15 miles, the Chagrin shale in the 

 Rocky River section is almost if not entirely barren of inver- 

 tebrate fossils. In the basal beds of the Cleveland shale, into 

 which the Chagrin grades laterally as shown in figure 3, 

 p. 204, a rich fauna of conodonts and great fishes occurs, some 

 of the latter having had a length of 20 feet or more. In the 

 sections to the west of Rocky River the fauna of the Chagrin 

 shale is represented only by an occasional I'aleoneilo or other 

 rare mollusc, while conodonts and the remains of great fishes 

 occur throughout the dark shales which, in this westerly region, 

 have been held to represent the lighter-colored Chagrin shale. 

 No one, we believe, who is familiar with the work of such 

 naturalists and geologists as Edward Forbes, Jeffries, and 

 Walther will deny that the great faunal changes briefly out- 

 lined above, which are found in following the Ohio shale 

 westward from the Pennsylvania line, are such as might be 

 expected in following a fauna in a line, normal to the direction 

 of its bathymetric facies. It will be instructive to give here 

 a brief summarized statement of the observations of Edward 

 Forbes on the zonal distribution of the marine life of the 

 British seas for comparison with the very similar zonal distri- 

 bution which characterizes the fauna of the Ohio shale. 



"British marine animals and plants are distributed in depth 

 (or bathyinetrically) in a series of zones or regions which belt 

 our shores from high water mark clown to the greatest depths 

 explored. The uppermost of these is the tract between tide 

 marks ; this is the Littoral zone." Littorina, Mytilus, and Fusits 

 are the dominant forms of this zone. Below low water mark 

 these mollnsca give way to other shells. The next or Laminarian 

 zone extends to a depth of about 15 fathoms. In this zone grows 

 the gigantic species of seaweed called Laminaria. Among these 

 live myriads of shell fish and other forms of life. The genus 

 Lacuna among the mollnsca is especially characteristic of this 

 zone. From 15 to 50 or more fathoms the majority of the inhab- 

 itants are predaceous. " Many of our larger fishes belong to this 



