Description of Four New Species of Echinodermata, from the Tertiaries of Contra Costa County.

BY AUGUSTE RÉMOND.

Astrodapsis Conrad.

A. Whitneyi Rémond.

Disk circular, or sub-pentagonal, slightly notched at the extremity of the ambulacra.

Apex central and elevated; edge depressed.

Ambulacral star symmetrical, prominent near the apex; petals equal, reaching to the margin of the disk.

Interambulacral spaces much depressed near the edge.

Lower surface slightly and gradually concave; furrows well marked and straight.

Mouth central, circular; anal aperture small, sub-marginal.

Papillary tubercles somewhat remote, smaller above than beneath, situated in wide and shallow cells; miliary tubercles very numerous and crowded, both on the superior and inferior surfaces.

Greatest diameter	1.8	inches
Smallest diameter	1.65	”
Height	0.3	”

Locality: Kirker’s Pass formations. Found in lower pliocene beds.

The genus astrodapsis, to which I have referred the above species, was indicated by Mr. Conrad, in the Pacific Railroad Reports, Vol. VII, Palæontological Report, page 196, without any generic description.

The genus is closely allied to clypeaster, but differs from it in having the petals of the ambulacral star extending to the edge of the disk, opened at the extremity, and in the margin of the disk being slightly notched at the extremity of each petal. The inter-ambulacral spaces are depressed. On the under surface there is a deep groove corresponding to each petal.

My collection, and that of the State Geological Survey.

A. tumidus Rémond.

Disk rounded sub-pentagonal, thick, rounded on the edge, very slightly notched at the end of the ambulacral areas.

Apex small, central, depressed.

Ambulacral petals symmetrical, very prominent, reaching to the margin, longitudinally grooved by a median line. The outer pores of the petals abruptly depressed on each side.

Inferior surface slightly concave.

Mouth central, small, rounded.

Ambulacral furrows straight, well marked.

Anus small, sub-marginal.

Papillary tubercles numerous, especially in the ambulacral areas, and in the center beneath, not prominent, situated in comparatively deep and sub-angular cavities.

Greatest diameter	1.34	inches.
Shortest diameter	1.26	”
Height	0.34	”

Locality: Kirker’s Pass formations; occurs as the preceding species; also two miles west of Walnut Creek House.

From the collections of the California Academy of Natural Sciences, of the State Geological Survey, and my own.

Echinarachnius van Phels.

E. Brewerianus Rém.

Disk small, oval-elongated, broader behind, rather thin.

Upper surface slightly convex; margin rounded.

Apex posteriorly sub-central.

Petals close, nearly symmetrical, the anterior and posterior ones the longest, as wide as or even wider than the inter-ambulacral spaces; ambulacral areas composed of very narrow plates, widening on the margin.

Inferior surface plane.

Ambulacral furrows not visible in the specimens examined.

Mouth small, central.

Anus very small, sub-marginal.

Papillary tubercles numerous, rounded, somewhat prominent, more crowded beneath than above.

Length	1.22	inches.
Width	1.06	”
Height	0.30	”

Locality: Two miles east of Walnut Creek House; from miocene beds.

Collection of the State Geological Survey, and mine.

This species is dedicated to Prof. W. H. Brewer, Botanist to the Survey.

Clypeaster Lamark.

C. Gabbii Rém.

Disk rather small, comparatively thick, varying from circular to sub-pentagonal and irregular sub-oval.

Apex nearly central, sub-elevated; margin rounded; genital apparatus sub-angular.

Ambulacral star almost symmetrical; petals about equal in length, elongated, open at their extremities.

Inferior surface flat near the edge, and gently concave in the center.

Mouth depressed, sub-central.

Ambulacral furrows straight, slightly marked.

Anal aperture very small, marginal.

Tubercles of the upper surface numerous, especially in the ambulacra, round and prominent.

Greatest diameter	1.16	inches.
Smallest diameter	1.10	”
Height	0.28	”

Locality: The C. Gabbii occurs abundantly on the eastern shore of San Pablo Bay, south of Mare Island, in soft sand-stones of miocene age.

Collections of the State Geological Survey, and Academy of Natural Sciences; also Mr. Gabb’s, Mr. F. L. A. Pioche’s, and mine.

Dr. Kellogg read the following paper: