MARCELLUS LIMESTONES OP LANCASTER 155 



aulopora Goldfuss 

 Aulopora sp. 

 A loosely branching corallum, probably of this genus, was 

 found attached to Orthoceras e r i e n s e . The upper half 

 is broken away showing only a longitudinal section. Budding 

 takes place, from the upper part of the corallites, and usually 

 from one side only, but at about every fourth or fifth individual 

 a bud is produced on both sides, thus giving rise to the loose 

 branching, characteristic of the species. This form resembles 

 Aulopora s u b t e n u i s of the Helderbergian, but, on 

 account of the imperfect preservation of the fossil, no specific 

 determination has been made. 



ceratopora Grabau 

 Ceratopora jacksoni Grabau, pi. 1, fig. 1 



Bost. soc. mat. hist. Proc. 28:415, pi. 1, 2 



Long branching individuals of this species are very common 

 in bed IV, and they occur also at Cayuga creek. Very perfect 

 specimens are found on the weathered surfaces, and fragments 

 from 1 to 2 inches long may be easily detached from the rock. 



Ceratopora dichotoma Grabau 



Bost. soc. nat. hist. Proc. 28:418, pi. 2, 3, 4 



Only fragments comprising two or three corallites were found. 

 They occur in bed V, Cayuga creek, and in the upper Marcellus 

 shale, bed F, at Plumbottom creek. 



CRINOIDEA 



Crinoid stems are of frequent occurrence in the upper four of 

 the limestone beds, but no other remains of crinoids have been 

 observed. 



ANNELIDA 



! spirorbis Lamarck 



Spirorbis sp. 

 Specimens showing the transverse section only are common in 

 beds VII and VIII, and they are found also in bed IV. They 

 are attached to Orthoceras marcellense and O. 

 eriense. 



