48 PALXONTOLOOT OF NKW-TOBK. 



Genus ST R M AT OC E R IU M. 



In the black marble of He la Motte, and in the same rock at Chazy, but more particularly 

 in the dark limestone containing the Colcmharia, we find numerous specimens of obscure 

 corals having a structure represented in figs. 2, 2 a and b. They are completely silicified, 

 so that the more minute structure cannot be decided ; but since they are abundant, and 

 require notice, I have proposed the provisional name of Stromatocerium, from tfrpufxa, -arof, 

 a layer or lamina, and nipiov, honeycomb. 



81. 1. STROMATOCERIUM RUGOSUM. 

 t 



Pl. XII. Figs. 2, 2 a, b. 



Coral hemispherical ; growth in concentric laminae or strata ; laminae numerous, wrinkled; 

 some faint indications of vertical tubes or cells. 



This coral usually appears as a rough shapeless excrescence upon the weathered surface 

 of the limestone ; but a little examination shows it to be composed of concentric layers, 

 which are evidently the skeleton of some coral. 



Fig. 2. A specimen, natural size, showing the concentric lamination of the coral. The masses are often 



several tjmes as large as this one. 

 Fig. 2 a. A fragment magnified, showing less contortion of the laminse, with some indistinct indication 



of vertical tubes or cells. 

 Fig. 2 4. A small portion of a specimen of the natural size, showing the rugose or contorted direction 



of the laminae. 



Position and locality. This coral, so far as known, is confined to the Black-river limestone, 

 and to the dark layers alternating with the Birdseye limestone. It occurs in the dark marble 

 quarried on the east side of He la Motte ; but this mass lies much above the Maclurea 

 magna, if not higher than the Birdseye limestone. It occurs at Chazy village, Watertown, 

 and other places. 



82. 2. CHJCTETES LYC0PERD0N1 



Pl. XII. Figs. 3, 5. 

 See Plates zxiii. and xxiv. Trenton limestone corals. 



A cylindrical branched coral ; branches somewhat clavate ; tubes fine, angular ; no 

 connecting pores visible. 



There is no apparent diflference between this species and the one so common in the 

 Trenton limestone. It is extremely rare in the Birdseye, though I have been led to suspect 

 its existence in many instances where the structure is wholly obliterated by crystallization, 

 as is the case with many other fossils of this rock. The same fossil, apparently, occurs in 

 worn ovoid fragments in the Chazy limestone, and its upward limit I have not yet as- 

 certained. It has, however, evidently a wide geological range ; coming into existence at 

 almost the earliest period of organic life, and is am(^g those rare forms that escaped de- 

 struction, or again came into existence after the final deposition of the Hudson-river group. 



