It is probably "more closely allied to some of the other species described by Prof. Hall of the HamiltonGroup under Troost's. Hertzer of the Ohio Geological Survey, to whom I am indebted for the use of some fine specimens from his own private collection. Indeed no trace of this character of margins is represented in the published figures or mentioned in the description of the species in question.
It splits and breaks the rock, exposing one side of the heavily wrinkled and striated ash. This species belongs to the section of the genus in which the umbonal slopes are rounded rather than angular, and the anterior surface in front of these slopes is not so clearly truncated or flat. Length, 2.90 inches; height, measured vertically from the most prominent part of the beaks to the horizon of the tips of the beaks, 6.5 cm; do.to cardinal margin behind the beaks, 1.93 inches; convexity, 1.40 in.
On the typical species of this genus there are no visible traces of oblique ridge and furrows, but it is good.
GASTEROPODA
I know nothing of the articulated, muscular, and pallial impressions of this shell, and refer it to Grammysia from its shape and general appearance. Height, measured directly from the most prominent part of the spire to the leading edge of the opening, 3.33 inches; height, to the most elevated part of the dorsal surface, when the shell is placed with the opening downwards, 1.44 inches; length and width of opening, each approximately 2.90 inches. The term "strong nodes" would also not apply to the numerous small, indistinct elevations that mark the positions of the spines on the internal casts of our species.
Body part more or less upwardly curved, slightly compressed behind, 'subangular on the right side, rounded over the dorsal or anterior slope, and gradually tapering posteriorly to the small free apex, which is composed of one-to-one and semi-contiguous volutions' ...and rotated to the right of the long axis of the free bid3^. This shell appears to differ from all described spiny species with which I am acquainted, in being more slender and elongated, and in having the small apex rotated almost perpendicular to the axis of the body part. 76 PROCEDURE OF THE ACADEMY OF . but its part is much straighter, while it is never so large and ventricose as in some varieties of that species.
It is an interesting fact that the above-mentioned European Devonian species represent both subgenera found in our coal-measures, the first belonging to the subgenus Trachydomia and the other to the typical section of the genus. It is probable that some of the so-called Naticas of European Silurian rocks belong to this genus, as may some of the American Silurian species referred to by Holopea, and other genera from. YY rapidly shrinking in size, those of the apex convex, the latter lar Dorsal girdle rather narrow, usually not raised above rounded dorsal surface, and simply defined by slight furrow along each. Newberryi, and appears to have its aperture somewhat less widened, though the specimens are hardly in a condition to show the widening of the aperture satisfactorily. Height of a medium specimen, 1.10 inches; width, 1.50 inches; height of opening, measuring to edge of rim, top of corner above, 0.95 inch; width, about 0.87 inch. Still, since it only shows the same number of movements in specimens of nine or ten times the volume of the typical specimen of that species, it is 1am. In large examples, where the strong striations of the first turns of the spire have been obscured by erosion, the specimens of this shell (which are usually preserved in such a condition as to present a perfect white lime appearance), appear to be of when viewed from above, strongly resembles the bleached shells of some of the large specimens. depressive forms of Hdicidese. These lines reach their greatest extent and are separated by spaces of their own width, about 0.5 cm from the apex, and beyond that they gradually become smaller and larger. They all feature a length of one-tenth of an inch. The difference, however, is that the transverse lines are smaller and busier, and there are about TO of them to the nearest centimeter, at the point where they are largest and widest apart. The crenulations of the transverse lines are also smaller and more crowded in the species under consideration, usually fourteen to the minute-tenth of an inch, which would amount to 140 to the inch; while according to the measurements of prof. WinchcU's so much larger and more distant in (\h(/- blis, that GO to 75 of them would occupy the same space. Barrande that this is due to the accidental removal of the top to expose one Niagaranensis, Hall, the species under consideration apparently it differs in that it tapers much more gradually, and has the transverse lines much smaller and more compressed towards the larger end of the shell. 1,2 and 3), but it has apparently not only attained a larger size, but differs in having its dorso-ventral diameter a little greater than the transverse, instead of being posterior. In terms of shape, it more or less matches some of the Bohemian species introduced by Dr. Barrande, but differs from all in surface markings; while it differs from his C.pugio^ which has a somewhat similar sculpture, in being a little more curved and without transverse waves. Volutes rounded — subquadrangular, with transverse diameter slightly larger than dorsoventral; rather broadly flattened at the periphery and compressed convex at the sides. Septa moderately distant or separated by spaces measuring about one-third the dorso-ventral diameter of volume 1871.] at the middle of each side. The surface (of the cast) ornamented with small transverse ridges, of which about thirty majl^e are counted on the side of each whorl, of which they occupy the outer half without passing over or to the periphery ; while on the inner volutions they are sometimes so short as to assume the form of transversely elongated knots. The maximum diameter of the specimen disk with the outer part broken off is about 9 inches; dorso-ventral diameter of the outer portion at the point where it is broken, more than 3.63 inches; thickness or transverse diameter equal at the same point, about 3.90 inches. If the last turn really be free, as it seems to be the case, this character would be equally opposed to the probability of it being a Nautilus; but as the specimens are not able to entirely remove all doubt on this point, it is scarcely possible that this one should perhaps be found to belong to some of the sections of that group, though I can scarcely believe it. Volutations about two and a half to three, rapidly increasing in size, somewhat larger dorso-ventral than transverse in diameter, moderately compressed on each side, narrowly rounded over the periphery, and regularly rounding into the umbilicus, which is of moderate depth and distinct narrower than dorso-ventral diameter of outer whorl. Septa rather distant, deeply concave on their anterior faces, and all crossing the sides and periphery with very slight backward curves; separated from each other on the peripher}^ space corresponding to approx. half of dorso-ventral diameter at point of measurement. Body chamber large, or constituting half of the outer movements; aperture not enlarged; lip tortuous on the outside. Cast surface showing some traces of fairly distant transverse ridges on the inner curves, which become almost or completely aged at the outer curve. Largest diameter across the disk of a specimen slightly compressed by accidental pressure, nine inches; dorso-ventral diameter of the last bend near the opening, 4.10 inches; transverse diameter of the same, 3.50 inches. It is another form in connection with the generic characters that I doubt. Mesial lobe rather depressed, but rounded and well defined, narrow, or only about two-thirds as wide at its front as the lateral lobes, tapering gradually, with straight sides, towards its posterior end, terminating at a distance of about half the breadtli of the anterior end, within the margin; provided with about twelve or thirteen almost straight segments, most of which are well defined. These furrows are so widely and strongly defined that I have somewhat doubted whether the}'" should not be regarded rather as the divisions between the segments (which in that case would be represented by the comparatively narrow intervening furrows) than as the furrows of the segments themselves. However, when they are followed inwards towards the mesial lobe, they are found to be abruptly narrowed and slightly bent forward as they approach it, so that they appear to correspond to the grooves on the segments, rather than to the depressions they form. to have. None of the specimens show much of the surface, but as far as... it can be seen, it appears to be smooth and exactly coincident [July 4. Mesial is narrow, or only equal to half the width of each lateral lobe at the anterior ends, depressed and gradually tapering towards the posterior end, ending very close to the truncated posterior margin; quite clearly separated 1) the furrows on each side of the lateral lobes; segments of about eighteen, crossing transversely and separated by Avell-. defined furrows, which are narrower than the segments themselves, which are not grooved. First, it differs in that the mesial lobe is only half as wide as each lateral lobe (measured both at their anterior ends), instead of only about one-third as wide (see dimensions of D. myrmecophorus given in Fifteenth Report, Regents Univ. Again no shows no traces of nodules or spines (except the marginal spines) on any of the segments, either of the mesial or latex lobes; whereas in Green's type the segments of the lateral lobes are described in the Regents' report above quoted, and also by Green, as they are labeled with one or two rows of nodes, and those in the mesial lobe are described in the Regents' Report as marked by three spines. Green gives the number of segments in their median lobe of the pj^gidium as fourteen, and in each lateral lobe as thirteen, while in the apparently larger specimen (3 inches in length). Hall counted twenty-four segments in the axis, and twenty in each lateral lobe; from which we can infer that the number of segments varied somewhat with specimen size in that species. Another specimen in the collection from the same place and position from which the foregoing description was made. It also differs in that the spines on either side of the truncated posterior end are clearly larger than in the form described above, and are directed straight backwards, as in D.PTEROPODA
CEPHALOPODA
CRUSTACEA
