24 



inner, black, horny layer and an outer, pkosphatic layer. Where 

 the outer layer is decorticated the surface is ornamented by trans- 

 verse, arching furrows separated by narrow, smooth, elevated lines; 

 but, where the outer layer is preserved, the furrows and ridges 

 are about equal in width, and the ridges become crenulated costje. 

 The cosipe are not regularly arched, but curve rather abruptly 

 across the mesial line and are then directed, in nearly straight 

 lines, inclined about ten degrees, to the furrows, at the angles. 

 There are about forty-five transverse, crenulated costae in an inch 

 in length. The specimen near the larger end, where best pre- 

 served, has a diameter one way of two and two-tenths inches, and 

 the other way of one and nine-tenths inches. It tapers, toward 

 the apex, in a distance of three and six-tenths inches, and in the 

 other of one and two-tenths inches. At the smaller end the speci- 

 men is broken off diagonally, and at the larger end an inch and 

 a half in length of one of the wider sides is bent down as if ap- 

 proaching the mouth, but the other sides are continued without 

 being bent and show the continuing enlargement of the shell. 

 The greatest length of any part of the shell, that is preserved, is 

 six inches. These measurements indicate that the specimen, when 

 perfect, exceeded ten inches, in length. The surface ornamentation 

 is altogether different from C. trentonensis, and the two species 

 can never be mistaken for each other by any palaeontologist. 



Species of Conularia have been described from Trenton, Hud- 

 son River, Niagara, Lower Helderberg, Oriskany, Upper Helder- 

 berg, Marcellus Shale, Hamilton, Portage, Chouteau, Kinderhook, 

 Waverly, Burlington, Keokuk, Warsaw and Kaskaskia Groups, and 

 from the Lower and Upper Coal Measures. The range is from 

 the early Trenton to the close of the Upper Coal Measures. 



The shells are all pyramidal, and vary, in different species, from 

 square and subquadrate, to octagonal and somewhat rounded. 

 They expand slowly or rapidly in different species, and, so far as 

 known, are contracted near the mouth. The mouth appears to 

 have been very large, and no operculum or other shelly covering 

 has ever been found belonging to it. We have examined more 

 than one hundred specimens of Conularia, and have never seen 

 the mouth of a single shell, so that what we have said about the 

 mouth is on the authoriiy of others. No muscular scar has ever 

 been found inside the shell or on a cast, by which the animal was 

 attached to the shell. The four angles of the shell are more or 

 less furrowed, and a mesial line, on each side, is always indicated, 

 and sometimes it amounts to a furrow. The shells are ornamented 

 with transverse lines and furrows and costse, some of which are 



