Disk sub-circular, broad, upper surface convex towards the middle, depressed on the margins, plane beneath; apex central; ambulacral star symmetrical; petals long, equal, closed at their extremities, nearly reaching from the apex to the margin of the shell, terminated by five or six irregular hexagonal plates. The petals are longitudinally divided into four rows, which are connected by numerous and regular transverse lines of pores. Mouth central; anus submarginal; ambulacral furrows symmetrical, not much ramified. Inter-ambulacral areas occupied by two rows of pentagonal plates, convex, of equal length, increasing in size until they unite with the ambulacral plates; hexagonal from that point and decreasing towards the margin.
Two sorts of appendages; spinous processes numerous and crowded, above and beneath. Spines of the superior surface short, striated, pyriform, irregularly pentagonal or hexagonal; inferior spines slender, comparatively long, dentaliform, striated longitudinally, tubular and round.
Obs.—Water-worn fragments of this fine fossil occur in abundance on the beach, between Merced Lake and the Pacific, south of Point Lobos, in San Francisco County. It was made known to science by Mr. W. P. Blake, Geologist of the Railroad Survey, who found it in 1853, among the shingles thrown up by the surf, and first described by Mr. W. Stimpson. At that time the locality whence the scutellæ were derived had not been discovered, so that the specimens obtained being imperfect, no complete description could be made; this is the reason why I offer a new and complete description of the Scutella interlineata, from specimens procured in situ. As was suggested by Mr. W. P. Blake, the rocks bearing these fossils are found a few miles southward, north of the boundary line between San Mateo and San Francisco Counties, where the scutellæ stick out from conglomeratic sandstones, which Mr. Gabb considers as belonging to the pliocene or post-pliocene formation; we find them in a fine state of preservation, with their spines retained.
The S. interlineata is figured in the Railroad Reports; see vol. V, Geological Report, plate IV, fig. 30; and for Mr. Blake’s remarks and Mr. Stimpson’s description, the same Report, chap. XII, p. 153.
Dr. J. Blake made some remarks on specimens, presented by him, of infusoria, found in the sand-hills, south of Point Lobos, and which form a kind of concretions, fixing the sand in its place.
Dr. Ayres made the following remarks in relation to the genus Notorhynchus:
This genus was defined by me in 1855 (Proc. Cal. Acad. Nat. Sci., vol. I, p. 72) to include a species occurring in the Bay of San Francisco. In 1858 Girard refers to the species (P. R. R. Rep., vol. X, p. 367) under the generic name Heptanchus, of which he considers Notorhynchus a synonym. In 1861, Mr. Gill refers it to Rafinesque’s genus Heptranchias. (Annals of the Lyc. Nat. Hist., N. Y., vol. VIII, Dec.) In a more recent paper (Proc. Acad. Nat. Sci., Phil., Oct., 1862) Mr. Gill restores my species to the name under which it was originally described. He says: “This generic name of Notorhynchus was proposed by Dr. Ayres under a misapprehension.” My “misapprehension” was that I regarded the species as the type of a new genus; a conclusion at which Mr. Gill himself has, after several changes, also arrived. He gives as a synonym of Notorhynchus only “Heptanchus, Sp. Müller and Henle, Gray, Girard, Gill,” whereas it is necessary to include also “Heptranchias, Gill,” as above indicated.
I may remark that the description given by Mr. Gill of the teeth of Notorhynchus maculatus, (Proc. Acad. Nat. Sci., Phil., Oct., 1862, p. 495) will not bear examination. It represents the individual specimen on which it was founded; but the species is quite common here, and I find that the number and the forms of the teeth vary so much, that my original description, which Mr. Gill says is “equally applicable to any species of the family,” is fully as close as nature will allow us to draw. I am at a loss to understand how it is possible for him to refer the jaws of a shark, collected at a point so far removed from us as Nisqually, to my species, when my description is so extremely indefinite.
Professor Whitney gave an account of an interesting collection of Japanese minerals and fossils, in the possession of J. H. Van Reed, Esq., of this city.