256 rAL^ONTOLOGT OF NEW-YORK. 



Fig. 1 o-. A fragment of a large buckler, having but two distinct rows of punctures in front of the 

 glabella. 



Fig. I k. A portion of the thorax and caudal extremity, from the glazed slate, at Waterford. The long 

 spine appears as if attached to the caudal extremity ; but it is scarcely in a direct line with 

 the axis of the specimen, and is not quite symmetrical on the two sides at its base. I am, 

 therefore, inclined to regard this as a spine from the buckler, which has been accidentally 

 placed in this position. 



I have not yet been able to find any marks of specific distinction among these fossils, 

 though I have examined more than one hundred nearly perfect specimens, and as many 

 fragments, from the slate and limestone. The small spine-like process at the base of the 

 glabella has not been heretofore observed, but it will be found to exist in all perfect speci- 

 mens ; the cause of its absence is fracture, which may often be obscure or indiscernible. 



I am indebted to Dr. Emmons for an opportunity of examining a beautiful collection 

 of specimens of this species, from the shales of the Hudson-river group, at Loraine. Many 

 of the small slabs are completely charged with them, and several hundreds were obtained 

 in the space of a few feet. 



Position and locality. This species is found throughout the rocks of the Hudson-river 

 group, occurring in the lower part of the same at Turin and Martinsburg. At Loraine and 

 Pulaski, this fossil occurs in the higher parts of the group ; and at Waterford, near Cohoes 

 falls, in the glazed and plicated slates of the same group. It has likewise been found in 

 one or two places in the Mohawk valley, in a similar position. (State Collection.) 



310. 1. OLENUS ASAPHOIDES. 



Pi.. LXVII. Figs. 2 o, b, e. 



Elliptocephalus asaphoides. Emmons, Tac. System, 1844, pag. 21, fig. 1,2,3. 

 — — Id. Agr. Report, 1846, pag. 65, figs. 1.2, 3. 



Compare Aiaphxu (Ogygia) Suehii, Brononiart, Crust, ibssiles, pag. 20, pi. 4, figs. 2 a b. 

 Aiaphus Buehii, Murcuison, Sil. System, pag. 662, pi. 25, fig. 2. 

 Ogygia (Asaphus) Buehii, Bvrmeister, pag. 69, pi. 1, fig. 2. 

 Olentu of DAXjf AN, Burmeister, &.C.* 



Buckler semielliptical or subcrescent-form, with the posterior margins produced into 

 sharp spines ; eyes indistinctly marked ; glabella lobed ; direction of the facial suture as in 



* The species under consideration is either an Olenus or Ogygia, as the genera of this class of animals are now 

 defined, and I therefore arrange it with the former for reasons to be given. The name Elliptocephalut could 

 •carcely be admitted, since the Ellipsocephalus of Zenker is so well known in its application to a very distinct 

 geDeric form. 



