24 



inner, black, horny laj-er and an outer, phosphntic layer. AVhere 

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

 vei'se, 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 bacome crenulated costaj. 

 The costfe are not regularly arched, but curve rather abruptly 

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

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

 There are about forty-five transverse, crenulated costa; 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 

 tlio otlier way of one and nine-tenths inches. It tapers, toward 

 tlie 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 lai-ger end an inch and 

 H half in length of one of the wider sides is bc>nt 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 tiie shell, tbat is preserved, is 

 six inches. These measurements indicate that the specimen, when 

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

 is altogether diH'erent from C. trentonensis, and the two species 

 can never be mistaken for each other by any pal.-cjutologist. 



Species of Conularia have been described from Trenton, Hud- 

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

 berg, Marcellus Shale, Hamilton, Portage, Chouteau, Kindeihook, 

 Waverly, Burlington, Keokuk, Warsaw and Kaskaslda Groups, and 

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

 the early Trtmton to the close of th(! Upper Coal Measures. 



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

 square and 8ub([uadrate, to octagonal and somewhat rounded. 

 'J'iiey expand slowly or rapidly iu different species, and, so far as 

 known, are contracted near the mouth. The month 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 Coimldrui, 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 costie, some of which are 



