GASTROPODA. 29 



stronger than the two others, but thinner still than the central one ; 

 we might divide the ribs according to their strength into four 

 orders, and the interstice between two ribs of first order, would 

 be filled out by one of the second, two of the third and four of the 

 fourth order, in the following sequence, 1st, 4th, 3rd, 4th, 2nd, 4th, 

 3rd, 4th, 1st order. These ribs are crossed by fine, equidistant 

 longitudinal striae which produce a kind of rectangular net work. 

 Aperture not known. 



Locality,—* Yenangyat, rare. 



Remarks. — This species is closely allied to F. condita, Brong.* 

 but in the latter species the revolving ribs are apparently much 

 stronger and the intermediate ribs much less regular than in the 

 species from Burma, 



TRITON (S1MPULUM) DAVIDSONI, d> Archiac, Plate VI, 



Fig. 6 — 6a. 



1853. Tritonium davidsoni, d' Archiac and Haime, Desc. des Anim. foss. du groupe 



nummulitique de l'Inde, page 312, plate XXX, fig. 3 a, b. 

 1879-80. Tritonium javanum, K. Martin, Tertiar auf Java, page 6o, plate 14, fig. 12. 

 1 880-81. Tritonium javanum, K. Martin, Beitrage zur Geolog. Ost Asiens and Au'straliens, 



vol. I, page 208, plate IX, fig. 9. 



The oblong shell consists of about six ventricose whorls ; spire 

 prominent ; surface covered with strong rounded and equidistant longi- 

 tudinal ribs, of which there are always three between two varices, 

 these are crossed by fine revolving ribs, which when crossing the 

 longitudinal ribs or varices, produce thereon a kind of horizontally 

 extended nodule, Aperture ill-seen ; outer lip thick and denticulated. 



Locality \ — Common at Minbu. 



Remarks. — The specimens from Burma are unfortunately very 111— 

 preseved, none of them having a complete shell, but the characteristic 

 sculpture of the whorls is so exceedingly well exhibited that there 

 is not the slightest doubt as to the identity. Messrs. D' Archiac and 

 Haime have compared this species with 7". reticulosum, Lam., but to 

 judge from Deshayes' figure 2 the resemblance is a very distant one. 



1 D'Archiac and Haime, Descript. des Anim., plate XXXI, figs. 2 and 2 a. 

 3 Coquilles fossiles des environs de Paris, pi. LXXXIII, fig. 2 and 3a. 



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