Page:Smithsonian Miscellaneous Collections, Volume 85.djvu/94

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Comparing this form with M. preciosa Walcott, the genotype, the new species is stouter and shorter. As none of the specimens referred to the type species preserves the rear end, it is not possible to determine whether the lobate termination of M. placida is also characteristic of the first species. The annulations of the body are clearly marked in the specimen illustrated, particularly on the counterpart, which is a mold of the exterior. Teeth are shown around the mouth as bright, shiny, curved, chitinous hooks.

Holotype.—U. S. N. M., No. 83928.


 * Canadia spinosa Walcott, 1911, Smithsonian Misc. Coll., vol. 57, no. 5, p. 118, pl. 23, figs. 4-7.

Original description.—"Body slender, formed of 20 to 21 segments that, when flattened on the shale, are a little longer than wide; each segment has a pair of parapodia with a dorsal and ventral bundle of strong non-jointed setae. The setae are finely illustrated by figures 4, 6, and 7. Head minute, with a pair of large tentacles curving outward from the front anterior margins; a bundle of fine setae occurs on each side of the head back of the base of the large tentacles. A straight slender enteric canal is indicated on several specimens. Mouth and anus not seen, but probably at or near the end of the annelid.

"Dimensions.—The largest adult specimen has a length of 34 mm., with a width of the body at the seventh segment from the head of 1.5 mm."

Fortunately many additional specimens of this interesting spiny worm were found after 1911. Those first illustrated give a fairly good conception of the general features; however, illustrations of additional specimens may show features particularly desired by the biological student at places where the other specimens are faulty.

Plesiotypes.—U. S. N. M., Nos. 83929a-e.