Crin. 162 



Crinoid stem. (Tricyclus ?) Vanuxem, Geology of the Third 



district 

 of N. Y. 



184 2, 



Vfllg, Vajt^AKl^ " " pagel82 



^^ fig. 49,6. 



Ilamilton formation, VIII g, 



Crustacea. — (1.) Fifteen families of 7rilohites^n}xmeA from 

 the typical ^enus of each family : Acidaspis^ Aglasjns^ Ag- 

 nostics^ Asaphus, Bronteus^ Calymene^ Cer aunts ^ Conocepha- 

 lus, CgphaSn liar pes ^ lichas^ Paradoxides. Phacops, Prmtus^ 

 Trmucleus. — (2) Insects in shells, like Cythere and Begrichia. 

 — (3) Prototypes of the lobsters, like Eiirypterus, (4) Many 

 other forms ot articulated animals, more or less covered with 

 shells. — Trllohites appeared in the earliest ages, in immense 

 numbers and of great variety, and continued to flourish into the 

 Coal Age, when the last species disappeared from the earth. — 

 The others appeared, so far as we know, much later, and have 

 also ceased to exist or been changed into other forms of the 

 same style of construction. — The minute bivalve crustaceans 

 are vastly abundant in the Clinton fossil iron ore heds (see 

 Beyrichia.) They are equally abundant in the highest coal 

 measures of Washington and Greene counties, in nearly all of 

 the limestone beds of the Upper Barren measures (K, p. 47) 

 especially in the Upper (white) Washington limestone (No. 6 

 of Stevenson's series) and in the fish bed over the Washington 

 Lower limestone (No. 2) K, pp.48, 50; al^omhlach sJiaJ e^^egro 

 run (p. Ill), at Washington (p. 149); Mack shale over L. 6, 

 Pursley run (p. 152); black shale parting in L. 2, Ten Mile 

 Village (p. 188); black shale over L. 3 (p. 225); Hack shale ^ 

 110' below Jolleyt.own coal (p. 225); in L. 2 & 4, Washing- 

 ton tunnel and 20' over L. 6 (p. 242); vast numbers in the 

 fetid L. 6 (p. 243); in slate partings of L. 6, under coal 

 (p. 261); in L. 6 (p. 28 1), — The larger crustaceans are occa- 

 sionally seen in the shales between the first and second Moun- 

 tain sands of Venango County, {SulGarhoniferous) (1, p. 37); 

 in Randall's Warren Section, division R, over the ''Reds" 

 (IlII, p. 306). The trail of one of these crustaceans is noticed 

 by White (Q 2, 70) on a flagstone, near Newcastle, Lawrence 

 Co., Pa., which contained many of the characteristic subcar- 

 boniferous Spirifers^ Producti. Allorisma^ &c., and many 



