306 Systematic Paleontology — Middle Devonian 



Coleolus tenuicinctum Grabau, 1899, Bull. Buffalo Soc. Nat. Sciences, vol. 



vi, p. 284, fig. 217. 

 Coleolus tenuicinctum Kindle, 1901, Twenty-fifth An. Rep. Dept. Geol. & 



Nat. Res. Indiana, p. 735, pi. xxiii, figs. 6, 7. 

 Coleolus tenuicinctiis Grabau and Shimer, 1910, N. Am. Index Fossils, vol. 



ii, p. 9, fig. 1219b. 



Description. — " Shell an extremely elongate, gradually and regularly 

 tapering cone ; having in the largest individuals, a diameter of six milli- 

 meters at the larger extremity, with a length of seventy-five millimeters. 

 Surface marked by fine closely arranged striae, or frequently with more 

 distant oblique aunulations, receding from the aperature, or sinuate on 

 the ventral side; interrupted longitudinal striae are visible in well pre- 

 served specimens." Hall, 1879. 



Hall also stated that the specimens were generally in a crushed condi- 

 tion and showed a line of fracture which may be mistaken for a longitudi- 

 nal groove while the diameter and length vary to a considerable degree and 

 no individual in the Hamilton shales has yet been found entire. Dr. J. 

 M. Clarke has shown the presence of septa in another species described by 

 Hall as Coleolus aciculum and hence referred it to the genus Bactrites 

 (Am. Geol., vol. xiv, 1894, p. 37, pi. ii, fig. 9) ; but so far as we are 

 aware this character has not yet been observed in C. tenuicinctum and 

 therefore the species is left in the genus Coleolus. 



The Mar3'land specimens are contained in an arenaceous shale and are 

 long tapering cones which are flattened with a conspicuous longitudinal 

 groove due to fracture. The more or less oblique annulations are well 

 shown, but the concentric and longitudinal striae, very imperfectly. The 

 specimens, however, are practically identical with many of this species 

 which the writer has collected and examined from the Hamilton shales 

 and there can be no question regarding their specific identity. 



Length of two longest specimens, which are broken and do not show 

 complete length, 55 and CO mm. ; width of both at larger extremity, 6 mm. 



Occurrence. — Eomney Formation, Hamilton Member. East bank 

 Evitts Creek below Wolfe Mill; west of Lock No. 56 at Great Cacapon. 



Collection. — Marjdand Geological Survey. 



