Page:Smithsonian Miscellaneous Collections, Volume 85.djvu/99

Rh posterior part of the body is broken off. The anterior pointed end of the head is broken off in such a manner that the presence of a frontal appendage is suggested. The large opening on the side of the head indicates a large pedunculated eye comparable with that of Opabinia regalis (pl. 28, fig. 1).

"Appendages.— Of the head appendages, the antennae are the best preserved. These are large and composed of several strong joints, of which three now show from beneath the carapace; the second of these bears a long slender branch on its inner margin, and the third two branches, one of which is similar to that of the second joint. These two branches appear to be composed of one very long slender joint followed at the end by several short small joints that curve upward and presumably gave the branches flexible extremities; the third and lower branch has a similar slender proximal joint that at its outer end has three slender, jointed branches. This structure makes a very effective clasper of each of the antennae. Back of the right antennae are two narrow appendages that may be the ends of one of the third and fourth pairs of head appendages.

"The thoracic legs terminate in flat, elongate, broad, lanceolate joints. The terminal joint is about three-fifths the entire length of the leg, and has a fringe of strong setae on its outer and posterior margin. The condition of preservation is such that the details of structure of the other portions of the leg cannot clearly be determined."

The illustrations presented herewith apparently were prepared by Doctor Walcott to exhibit the detailed structure of this interesting crustacean.

Plesiotypes.—U. S. N. M., Nos. 83943a-g.

Several specimens, of which the best is illustrated, were labeled Leanchoilia major by Walcott. Just why he should have chosen this specific name is not readily apparent as these individuals are not sufficiently larger than L. superlata to warrant the designation. In fact there is but little difference between this form, which happens to be flattened out horizontally, and the specimen shown in figure 2, plate 13, referred to the genotype.

Holotype.—U. S. N. M., No. 83944.


 * Naraoia compacta Walcott, 1912, Smithsonian Misc. Coll., vol. 57, no. 6, p. 175, pl. 28, figs. 3, 4.

Many specimens of this interesting form have been found since its preliminary description in 1912, but none shows the cephalic