TERTIARY FOSSILS. 61 



near the port of San Bruno and vicinity, north of Loreto, on the east side of the 

 Peninsula of Lower California. At this locality, most of the specimens are six 

 inches or more in diameter, very thick, and quite flat, the ribs being much more 

 numerous, and somewhat smaller than in the specimens from which my original 

 description and figure were taken. 



O. Cei-rosensis was found associated with it at San Bruno, and I have recently 

 received from Prof. Raimondi, of Lima, a shell from the Post-Pliocene of Peru, 

 which seems to be identical with the latter species. 



TAMIOSOMA, Conrad. 



T. GREGAR1A, Cotl. 



PI. 18, Fig. 22, a, b, c, d. 



(Tamiosoma gregaria, Con. ; Proc. Phil. Acad., 1856, p. 315.) 

 (Tamiosoma gregaria, Con.; P. R. R. Rep., Vol. 6, p. 72, pi. 4, fig. 18.) 

 (Balanus Estrellanus, Con. ; P. R. R. Rep., Vol. 7, p. 195, pi. 8, fig. 1 ) 

 (Radiolites grega~ia. Con. ; Proc. Phil. Acad., 1864, p. 214.) 



This problematical fossil was described by Mr. Conrad almost simultaneously in 

 the Proceedings of the Philada. Acad. Nat. Sciences, and in the sixth volume of 

 the Pacific Railroad Reports, as follows: "An elongated tube, apparently entire, 

 porous and cellular throughout its substance ; interior filled with numerous regu- 

 larly disposed vaulted cells, connected by longitudinal slender tubes, funnel-shaped 

 beneath; aperture resembling that of Balanus." 



" T. gregaria. Subquadrangular, elongated, longitudinally furrowed and (striate, 

 and having fine, undulated, transverse lines ; mouth small, oblique ; upper part of 

 the tube oblique, deeply indented or Balaniform, and coarsely striated longitudi- 

 nally. Length, eight inches." He further remarks : " Growing in clusters, like 

 Balanus. No sutures indicating separate valves ; cells very thin plates, convex 

 surface downwards." 



From the above, it seems either that Mr. Conrad had no opinion as to the rela- 

 tions of this shell ; or from his repeated comparisons with Balanus, that he ap- 

 peared to have suspected it of being a Cirrhipede ; and he accidentally redescribed 

 it as such, in the seventh volume of the P. R. R. Reports. 



In 1864, however, in the course of some "rectifications," he quotes it as a Iia- 

 diolite, without other remarks than that it is characteristic of the Cretaceous of 

 California. 



Though since found at a number of localities in the State, it seems to be always 

 rare. I had not the good fortune to encounter it, until in the summer of 1866, 



