MIOCENE ECHINODERMATA. 185 



The ambulacra! areas are rather wide at the margin, where they equal or exceed the inter- 

 ambulacral areas, widening rapidly from the ends of the lateral and posterior petals, less rapidly 

 from the odd petal ; dorsal portions petaloid . The petals are relatively short, almost symmetrical 

 as a group, almost equal in size, extending from one-half to almost two-thirds the way to the 

 margin, all but the odd petal subelliptical in outline, tending to close at the ends; the odd petal 

 noticeably differs from the rest in form, having its inner rows of pores diverging gradually to the 

 end, which is wide open, much more so than that of the other petals. The poriferous zones are 

 relatively wide; pores oval; pairs of pores conjugated; interporiferous areas of the anterior 

 paired and posterior petals rather narrow, not much wider than the poriferous zones, that of the 

 odd petal considerably wider, especially at the outer end of the petal. Several pairs of pores, in 

 strongly diverging rows, extend beyond the ends of the petals. 



The interambulacral areas are all rather narrow between the petals, broad from about oppo- 

 site the ends of the petals to the margin. The surface of the test is covered with small uniform 

 tubercles, which are somewhat larger on the under surface, especially near the peristome. 



The apical system is central or slightly excentric anteriorly and about coincident with the 

 apex. The details are obscure on the specimens, but there are four large genital pores of which 

 the two anterior are nearer together than the posterior pair. 



The peristome is central, or subcentral, slightly depressed; ambulacral furrows, according to 

 Pack, are "deep and traceable to the margin, " where they "show a slight tendency to branch." 

 On the specimens studied they are not well shown. 



The periproct is very small, supramarginal; sometimes located at a distance from the edge 

 equal to its own diameter. 



Related forms. — S.fairbanJcsi is most closely related to S. gabbi (Kemond) Merriam, but dif- 

 fers from it, according to Pack, in "attaining a greater size, in having a slightly undulating mar- 

 ginal outline, in having deeper and better marked furrows on the aetinal surface, and in having 

 the anal pore entirely upon the upper surface." S. fairbanlcsi is also allied to Dendraster 

 interlineatus and D. oregonensis, but may be easily separated from both by its more central 

 apical system, shorter and more equal petals, and wider marginal area. It also differs from 

 D. oregonensis in having the posterior poriferous zones of its paired petals curving. 



The specimen figured by Arnold as ScuteUa merriami was probably a young specimen of 

 S. fairbanlcsi. 



Localities. — Near Torrey Canyon wells, southwest of Piru, Ventura County, Cal. (Arnold); 

 Sespe Canyon, Ventura County, Cal. (Pack, Arnold). 



Geologic Jiorizon. — Vaqueros formation, lower Miocene. 



Collections. — U. S. National Museum (16496.3, B, C); University of California (A). 



Sctjtella (?) merriami (Anderson) . 

 Plate LXXXY, figures 7a-c, Sa-b. 



Astrodapsis merriami F. M. Anderson, 1905, California Acad. Sci. Proc, 3d ser. Geology, vol. 2, No. 2, pp. 193-194, PL 



XIV, figs. 33, 34. 

 ScuteUa merriami Arnold, 1909, U. S. Geol. Survey Bull. 396, p. IS. 

 IScutellamerriami Arnold, 1909, figure, U. S. Geol. Survey Bull. 396, PL VI, fig. 4. 

 ScuteUa merriami Arnold and R. Anderson, 1910, U. S. Geol. Survey Bull. 398, pp. 85, 86, 87. 

 tScutella merriami Arnold and R. Anderson, 1910, figure, U. S. Geol. Survey Bull. 398, PL XXVIII, fig. 4. 

 Sismondia merriami Stefanini, 1911, Soc.geol. italiana Boll., vol. 30, p. 702. 



Description. — This little echinoid was first described and figured by F. M. Anderson in 1905. 

 Its button-like appearance and its abundance in certain deposits in the Coalinga district of Cali- 

 forniahave led to these deposits being designated Button beds. The writer has had about 20 

 specimens from the Button beds available for study, most of which probably belong to this 

 species; but most of them were in poor condition and as the t} T pe could not be secured for com- 

 parisons the description of F. M. Anderson is here given verbatim: 



Bisk small, circular, depressed; margin only slightly notched at the ambulacral extremities; apex central, only 

 slightly elevated, star symmetrical, petals equal but not reaching the margin of the disk, and slightly elevated; anal 



