OP SOUTHEEN INDIA. 289 



Por some species of which he calls S, bioculata, d'Orb., the type, he proposed 

 the name DorUgnia, ( ? Orbignia), and a third group of which S. monilifera from 

 Jamaica is the type he calls Barrettia (vide Geologist, 1862, p. 375). DorUgnia is 

 said to have the hinge-rib obsolete, but this appears to be the case only in some 

 specimens in which it becomes obsolete near the peristome of the shell. Such is also 

 often the case in Sph(Erulites and Radiolites, In Barrettia the hinge-rib also becomes 

 obsolete near the aperture, but exists below in the interior of the lower valve, 

 and the outer layer of the shell is reduced to numerous narrow columns of different 

 length, entirely cemented by the inner layer of the shell, which besides occupies 

 the whole interior of the valve. I have not seen either JB[. Uoculata or monilifera, 

 but the character referring to the sooner or later disappearance of the hinge-rib near 

 the peristome, pointed out, seems to me to be of little importance, and I have 

 great doubt that it can be used even in a sub-generic sense. The structure and 

 thickness of the various species of Sippurites vary enormously, and the way in 

 which a shell has been preserved often alters a good deal its aspect. 



Zittel in his admirable Monograph* of the Gosau Budistce suggests that two 

 more sections can be distinguished, one represented by H. organisans and the other 

 by S, dilatata. The first has the outer shell layer not much developed, but still 

 more than S, moniliferus and most other Bippurites which are not strongly ribbed. 

 H. dilatata has the anterior muscular impression situated on a laminar projection, a 

 character which also appears to be common to many other species of Hippurites, 

 Parts of it are distinctly preserved in our specimen of Hipp, radiosa, Desm. 



4. Tamiosoma, Conrad, 1856. The type of this genus is a very peculiar fossil 

 from the upper miocene deposits of California, T. gregaria, Con. Gabb in the 2nd 

 volume of the Palaeontology of California (pp. 61-63) has very ably discussed the 

 organization of this fossil, and comes to the conclusion that it is most likely a 

 species of the Hippuritidje, The specimens which have up to the present been 

 found resemble the elongated, lower valves of Sippurites with a small place of 

 attachment apparently at the thinner or lower end. They are sub-cylindrical 

 with rather thick walls consisting of two or three layers, possessing the same 

 reticulated and striated structure as that of Badiolites, and others. The lower 

 portion of the shell is composed of a large number of irregular chambers or septa 

 which are produced by lateral prolongations of the inner wall. The end is occupied 

 by a large cavity, similar to the ' body-chamber' of Rippurites, but no impressions 

 of teeth have as yet been observed in it. The outer surface is longitudinally 

 striated in the type species which grows in clusters, as does, for instance, H, 

 organisans, Defr. 



When I first saw Conrad's description and figure of this species the irre- 

 gularity of the chambers or septa gave me the impression that the fossil might be 

 a coral, but the more detailed description of Gabb, though it does not altogether 

 remove that impression, — certainly points out aflinities which are very much in 



* Denk. Akad., Wien, vol. xxv, pt. 2, p. 135. 



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