690 Systematic Paleontology— Upper Devonian 



Genus PHARETRELLA Hall 



Pharetbella tenebrosa Hall 

 Plate LXXI, Fig. 10 



Pharetrella tenehrosa Hall, 1888, Pal. of N. Y., vol. vii, pt. ii, Supplement, 

 p. 7, pi. cxiv, figs. 30, 31. 



Dcscri'ption.—liSiW gives no description of this species save as it is 

 contained in the description of the genus Pharetrella which is as follows : 



" Shell large, elongate, Hyolithes-like in outline ; apex acute, transverse 

 section probably triangular, substance tenuous; ornamentation consisting 

 of transverse, imbricating undulating striae." 



Occurrence. — Jennings Formation, Genesee Member. Jennings 

 Eun Eoad, west of Corriganville. 



Collection.- — -Maryland Geological Survey. 



Class CEPHALOPODA 



Subclass TETRABRANCHIATA 



Order NAUTILOIDEA 



Suborder ORTHOCHOANITES 



Family ORTHOCERATIDAE 



Genus ORTHOCERAS Breyn 



Orthoceras consortale Hall 

 Plate LXXI, Figs. 16-18 



Orthoceras consortale Hall, 1886, Fifth Ann. Rept. N. Y. State Geol., pi. ii, 



figs. 3-5. 

 Orthoceras consortale Hall, 1888, Pal. of N. Y., vol. vii, Supplement, p. 29, 



pi. cviii, figs. 3-5. 



Description. — " Shell straight, rapidly expanding from the apex to near 

 the aperture; transverse section broadly oval. Apical angle ten degrees. 

 Initial extremity unknown. Chamber of habitation not fully shown in 

 the specimens observed, apparently short and constricted near the aper- 

 ture. Air chambers 5 mm. in depth, Avhere the tube measures 28 mm. 

 in greatest diameter. But little variation in the depth of the air 



