NEWTON : ON BORNEAN JURASSIC SHELLS. 409 
be more in favour of a Lower Oolitic or ‘Brauner Jura’ horizon.'! 
Moreover, some of Vogel’s species appear to share affinities with Lower 
Oolitic mollusca, as we know them in European and British rocks. 
His Pteroperna sp. closely resembles P. costatula of Deslongchamps ; 
the Astarte Eastoni exhibits a divaricate sculpture which is observable 
in Lycett’s A. (Ptychomya?) Agassizi (Ann. & Mag. Nat. Hist., 
ser. 1, vol. vi, 1850, p. 408, pl. xi, fig. 6); and Pholadomya cf. 
multicostata shows a strong resemblance to P. acuticostata of J. de C. 
Sowerby. 
According to Dr. Vogel, globose and oval Protocardie denote a 
Weisser Jura age; but it must not be forgotten that such forms as 
are common in the Bornean rocks under the names of P. erassicostata 
and P. tenutcostata occur also in older Jurassic beds, for in the 
Bathonian of England it is only necessary to quote P. lingulata and 
P. Stricklandi of Morris and Lycett as examples, the former showing 
coarse and the latter fine concentric sculpture. 
The new species of Zrigonia, now added to this fauna, strengthens 
this supposition, since its main characters are only to be found in 
forms common to the Bajocian or Bathonian strata of the Jurassic 
system. 
Dr. Krause, as previously mentioned, has described Ammonites from 
the same territory of Western Borneo, which come nearest to the 
European shell Harpoceras radians, consequently indicating the 
presence of Lias rocks in that area. It seems probable, therefore, 
that the Jurassic shells described by Martin and Vogel should belong 
more properly to Lower Oolite times, since rocks of that age would 
then immediately succeed the Lias beds just referred to, thus estab- 
lishing the sequential order of the strata in that part of Western 
Borneo. 
EXPLANATION OF PLATE XVI. 
Triconta MoLENGRAAFFI (n.sp.). 
1. Side view of a left valve. x 2. 
2. Areal aspect of a right valve. x 2. 
3. Side view of a left valve. Nat. size. 
», 4. Side view of aright valve. x 2. 
5. Inner view of same valve, showing teeth with obscure striations. x 2, 
», 6. Magnified (x 8) clavate intercostal ridges, bearing oblique striations. 
Figs. 1, 2, and 6 are drawn from wax impressions of casts found in the grey- 
cindery rock. Figs. 3, 4, and 5 are drawn from highly mineralized specimens found 
in the red ferruginous rock. 
PsEUDOMONOTIS sp. 
Fic. 7. Fragment of a lower valve, showing the minute fistulosities on the ribs, and 
the transversely striated intercostal grooves. x 2. 
This figure is drawn from a wax impression of cast found in the grey-cindery - 
looking rock. 
*,* For explanation of Figs. 8 and 9 see ante, p. 345. 
1 These remarks on Perisphinctes have been kindly confirmed by Mr. G. QC, 
Crick, F.G.S. 
