-512 RESEARCH IN CHINA. 



to 27, are irregular. They are often alternately long and short, but in parts of the 

 same corallite may be equal, or in appearance replaced by vesicular tissue. Not 

 infrequently one of the smaller (secondary) septa is seen to bend to one side and to 

 become confluent with a primary one. The interseptal loculi are rather abundantly 

 partitioned by what in cross-sections looks like dissepimental tissue but in reality 

 has more the nature of nearly flat horizontal tabulae. As previously remarked, the 

 septa are often so contorted that they can not be distinguished from the interseptal 

 plates with which they intersect. 



The pseudocolumella, which occupies the central area, is fairly distinct from 

 the surrounding structures and consists of relatively small concentrically arranged 

 cysts, which are nearly vertical in position but with the upper end distinctly inclined 

 toward the center. The ends of the septa reach nearly or quite to the pseudo- 

 columella, and some of them appear to connect with the plates which compose it. 



As members of the genus Lithostrotion, Lonsdale described and figured a number 

 of Lonsdaleiae from Uralian Russia, some of which may be related to the form under 

 consideration. Lonsdale discriminated his species upon characters which are not 

 shown in ordinary conditions of preservation, not, for instance, in the Chinese 

 material, and at the same time failed to give precise data regarding features which 

 I was able to ascertain. On this account a satisfactory comparison of the present 

 form with his species can not be made. It seems to be distinct from the American 

 and European types whose descriptions I have seen. No species belonging to the 

 genus has as yet been described from China. 



Locality and Horizon. Pennsylvanian (Wu-shan limestone) ; near Ta-ning-hien, 

 East Ssi'-ch'uan (stations i and 2). 



Michelinia favositoides Girty. 



Plate 29, Figures i, 2. 

 Michelinea favositoides GIRTY, 1907, Proe. U. S. Nat. Mus., vol. xxxin, p. 38. 



Of this species our collection contains a single specimen, which presents the 

 following characters : 



The shape appears to have been hemispherical, with a flat base and a width 

 greater than the height. The latter dimension is estimated at about 40 mm. and 

 the entire width at about 80 mm. The corallites are rather regular in size and 

 shape, and usually small, few of them attaining a diameter of 2.5 mm. The septa 

 are closely approximate, n to 13 occurring in a space of 5 mm. They are on the 

 whole rather regular, but are distinctly convex and not infrequently confluent. 

 Mural pores appear to be present, but, as shown in transverse sections, they are 

 rather rare, and their arrangement has not been determined. 



Any statement as to septa depends upon the interpretation of certain appear- 

 ances in thin sections. The bounding walls are not thick and show a dense median 

 line, which is usually more or less wavy. On either side of the median line is a 

 tolerably thick layer, intermediate in transparency between the material filling the 

 intertabular spaces and that of the median plate. The inner edge of this supplemen- 

 tary wall is rather strongly denticulate, the projections being in some places rather 

 regular and in other portions of the same corallite absent or irregular. Whether 

 these projections are really denticles or are continuous ridges has not been ascer- 

 tained. The tabulae show the same degree of transparency as the supplementary 

 wall, the projections of which can apparently with justification be interpreted as 

 pseudosepta, the dense median line being the plane of cleavage separating the truly 

 double-walled corallites. It is hardly possible to count the pseudosepta or to 

 ascertain the average number present. 



