Cerion regula Maynard, 1894

Original Description

"STROPHIA REGULA Novo.

Regular Strophia.

FIG. 52, A, side, B, front view of type.

DESCRIPTION.

            SP. CH. Size, large. Shell, not very thick. Striations present. Whirls, twelve. Examined fifty specimens.

            Form of shell a pointed cylinder, with the first, second and third whirls about equal in diameter, the fourth is but a little smaller, then the shell slopes to an acute point, forming an angle of sixty-two degrees. The first whirl is comparatively short, being only as long (measured in front) as the next four whirls below it, all together. The second whirl is shorter than the third and fourth, together, then each successive whirl is shorter than the next two below it. The striations are numerous, twenty-nine to the first whirl, they are narrow, about as wide as the interspaces between them, are rather angular, but are slightly flattened on top, not furrowed, but smooth, are very regular, and of about the same width for their length on each successive whirl, and are arranged in lines with scarcely an interruption on each line, from the first whirl to the apex.

            Aperture, rather small, arched and about as high as wide, and is slightly contracted at the entrance.

            Margin, produced forward about as far as the diameter of the shell, is slightly inclined to the right, a little beyond the diameter of the shell, is thin, about as thick as the shell behind it, with the edge smoothly rounded. Behind it, the shell is much roughened with lines of growth, which, on the sides project, showing an incli­nation to form a double margin. The frontal bar is well developed, protrud­ing considerably beyond the striations, and is about as thick as the margin.

            Color of shell, dull white through­out, pale brown within, becoming paler on the margin.

DIMENSIONS.

            Size of type, 1.50 by .60. Largest specimen, 1.50 by .63; smallest, 1.15 by .50. Longest specimen, 1.50; shortest, 1.15. Greatest diameter, .62 ; smallest, .50.

OBSERVATIONS.

            As all the specimens of this fine shell that I ever saw were occupied by a species of hermit crab, which always smooth away any inequality in the shells of which they take possession, the teeth were always worn nearly or quite away. Judging from the remains of the lower in the type, I should say that it had been large and prominent.

            Individual variation is toward a smaller form, 1.15 by .50, with eleven whirls, and also toward a form with more widely-apart and less regular striations, but all preserve the short upper whirl which is so characteristic of this species. In S. glans, S. bimarginator, and other species found on Andros, as far as I have seen them, excepting one to be described later, the upper whirl is about as long as all the other whirls together. Aside from this peculiarity, S. regula may be at once distinguished by the large size, narrow, equally wide striations, arranged in lines across the rather narrow whirls, which have shallow sutures, that are not notched, thus the whole combination makes up one of the most beautifully regular species of Strophia that I have ever seen, being excelled in this respect only by S. dallii, from Inagua, but, of course, S. dallii belongs to an entirely different sub-genus; see page 130 of Vol. I of these Contributions.

            Since a large portion of the present instalment of my monograph has been put into type, I have received Dr. Dall's paper on the shells collected during the" Cruise of the Steam-yacht' Wild Duck' in the Bahamas, January to April, 1893, in charge of Alexander Agassiz," which paper occupies No.9, of Vol. XXV, Bulletin of the Museum of Comparative Zoology. On pages 121 to 123 of this paper Dr. Dall has named the groups which I suggested were clearly separable, considering them, as being at least sub-generic.

            Dr. Dall's names for the sub-generic groups suggested by me are as follows, the characters, however, are from the earlier pages of my Monograph:

1. DIACERION.

LOWER TOOTH GREATLY ELONGATED, CHANNELED; POSITION CEN­TRAL. S. dalli Mayn. is Dall's type.

2. STROPHIOPS.

LOWER TOOTH ELONGATED, SIMPLE; POSITION CENTRAL. Type given by Dall, Pupa ducamana Fer.

3. MAYNARDlA.

LOWER TOOTH, SHIRT, SIMPLE; POSITION CENTRAL. Dall's type is S. neglecta Mayn.

4. CERION.

LOWER TOOTH, SHORT, SIMPLE, POSITION NOT CENTRAL. Dall's type is Turbo uva Linn.

5. EOSTROPHlA.

LOWER AND UPPER TEETH ABSENT. Type, E. anodonta Dall. This last group was defined by Dall in Cf. Trans. Wagner Inst., Vol. III, No. 12, August, 1890.

            As an additional sub-generic character for Maynardia I will add that the young of all the Bahama Strophias, with one exception (see S. bimarginata), which I have examined belonging to this sub-genus have a single tooth, there never being even an indication of any other (see fig. 33, page 108, of this volume of Contributions and compare with figs. 1, D, and 5, C, plate II, vol. I. .

[Note. In the paper cited above, Dr. Dall shows that the name Strophia Albers. 1850, must be abandoned for this genus, as it has not only been superceded by Cerion Bolton, 1789, but has also been preoccupied in Entomology (Mergen, Syst. Beschr. III, 147, 1832). To avoid confusion, however, I shall continue the name of Strophia until the close of this Monograph.]

HABITS AND DISTRIBUTION.

            The only specimens that I ever saw of this beautiful Regular Strophia, were, as remarked, occupied by the young of a species of Hermit crab, Diobeta diogines, and appeared to be quite a favorite shell with them. The crabs with their adopted shells were found on both sides of Fresh Creek near the settlement. Some of the shells appeared to be quite old and much stained, but some were compara­tively fresh; for example, the type, which I have figured, aside from the wearing away of the teeth and a small hole broken near the margin on the left side, is perfect, and the color of the internal parts is well preserved. But we could not discover any living specimens anywhere, although we searched with great care. It is probable, therefore, that Strophia regula is also an extinct species; but still it is possible, that the shell is to be found at some distance up the creek, the specimens found having been brought down by the out-going tide, and stranded on the shore where they could be found by the crabs. But I made a careful search of both banks of the creek for at least two miles from the settlement, and found no trace of a Strophia, of any kind, after leaving the immediate vicinity of the settlement. Then again, I do not think it probable that a species of Strophia would occur far from the coast, for I have never found one far from the sea."

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