MARCELLUS LIMESTONES OF LANCASTER 171 



coLEOLUs Hall 

 Coleolus tenuicinctus Hall 



Pal. N. Y. Yol. 5, pt 2, p. 185, pi. 32 



A single specimen in bed I, shows the faint striae character- 

 istic of the species. Several specimens in bed III are referred 

 with doubt to this species. The shell is replaced by finely 

 crvstallized calcite and the surface markings consequently 

 obliterated. The largest specimen observed has a length of 65 

 mm and greatest diameter of 5 mm. 



CEPHALOPODA 



ORTHOCERAS Brovn 

 Orthoceras exile Hall ' 

 Pal. N. Y. vol. 5, pt 2, p. 290, pi. 39, 84, 85 

 This species is fairly common in beds I, II and III. The speci- 

 mens are molds of the interior. The apical angle is about 6°, 

 and the depth of the air chambers is from 3 to 5 mm. The 

 largest specimen is 75 mm long, and retains a part of the living 

 chamber and 12 septa. 



Orthoceras marcellense Vanuxem 



Pal. N. Y. vol. 5, pt 2, p. 278, pi. 38, 39, 93 



This species, like O. exile, is represented by internal molds 

 which are somew^hat compressed. They are identified by means 

 of the distant septa and regularly enlarging tube. The apical 

 angle is 8°, and the depth of the air chambers 6 to 8 mm. The 

 largest specimen is 125 mm long, and a part of the living cham- 

 ber and nine septa are preserved. The position of the siphuncl^ 

 could not be determined. 



Orthoceras eriense Hall 



Pal. N. Y. vol. 5, pt 2, p. 274, pi. 40 



A fine specimen of this large species was found in bed VII. 

 It is 180 mm long, and 45 mm wide at the smaller end. It shows 

 a part of the chamber of habitation and nine air chambers, 

 which vary in depth from 9 to 13.5 mm. The apical angle is 7.5°. 



