lit; 



Report of the State Geologist. 



may cover one-third of the lateral slope of the whorl, but gradually become 

 broken up into shorter, irregularly branching, discontinuous, often comma- 

 shaped lines having a general direction toward the periphery. At the 

 periphery the)' become more strongly elevated and have their larger axes all 

 lying in the direction of revolution. 



Distribution. Tornoceras uniangulare appears first in the bituminous 

 shales, of the Marcellus division and is distributed rather sparsely throughout 

 the fauna of the Hamilton shales. In the Tully limestone it is rare, in the 

 shales of the Genesee it is seldom seen, though it abounds in the Styliola lime- 

 stone on Canandaigua lake and at Middlesex, Yates county. In the Naples 

 beds it occurs more sparsely than in the prenuncial fauna, but frequently 

 appears in the calcareous concretions of the lower part of the group in the 

 Honeoye lake valley, occurring also in the shales in Naples valley. "West of the 

 Genesee valley the species is of rare occurrence in these beds. Specimens of 

 large size are far less frequent in the Intumescens-fauna than in the Marcellus 

 and Hamilton shales beneath. No specimen has been observed from the 

 Portage group with a diameter exceeding 50 mm., but the State Museum pos- 

 sesses an imperfect shell from the Marcellus shale at Le Roy, whose diameter 

 was not less than 160 mm. 



The Portage fauna of Cortland and adjoining counties contains this 

 species with others, together derived from the Hamilton fauna beneath. 



Tornoceras uniangulare, var. obesum, var. now 

 This variety is characterized by the much greater thickness and tumidity 

 of the whorls. The feature is recognizable in both young and adult forms 

 and at any given stage of growth it is noticeably distinct in this respect 

 from the normal specific form at the same stage. It is undoubtedly an 

 instance of a long continuance of immature conditions in the normal, serving 

 as a differential in the adult. 



This form is ol rare occurrence and has been observed only in the concre- 

 tions at Naples and on the lake Erie shore. 



ToRNOCKKAS UNIANGULARE, vai\ COMPRKSSUM, var. liov. 



The specimens from the Hamilton shales at Wende Station, Erie county, 

 Upon which Beecher based his observations of development changes, are 

 laterally compressed shells with a subangular periphery. Even in early 

 stages of growth, at the third volution, when the normal shell is very rotund, 

 this compression is observable. These characters are accompanied by a clear 



