14 SECOND YARKAND MISSION. 



tubes pass out radially on them, and the orifices are only seen ; others come up to the surface 

 and hend down again suddenly, leaving a geniculate swelling visible ; and others enlarge 

 and diminish in their caliber. Some of these pass along the surface for a very short distance, 

 and all very close together laterally, and others pass up the flanks of the eminences converging 

 close to the summit and opening on them with their orifices, or more frequently on the 

 centre of the tubercular elevations. 



The pores are numerous, small, shallow, and universal; they are limited by lateral 

 tubes, and some open on their floor. The fossilization is by calcite, and in many places 

 the interspace between the surface tubes infiltrated with calcite has been preserved, the tubes 

 having weathered away. The tubes are so close together that the infiltrated calcite is difficult 

 to distinguish from tube ; but its breadth is usually much the smaller. 



In radial sections the radial series of tubes are numerous and large, but the interradial 

 systems are not very distinct from them, there being no wide tube reticulation. 



The tubes of the radial series are rather close, large, bifurcate, varicose, geniculate often, 

 suddenly diminishing in size where joining others ; they join much with each other, side by 

 side, are usually distinctly radial in their direction, which, however, is locally irregular, and 

 they have thin walls and a large caliber. 



The interradial tubes, very radial in their course, however, are often seen passing for short 

 distances, parallel with the circumference, in all parts of the body. They are more varied in 

 their courses than the radial series, and are usually close together and crowded, the distance 

 between them being small. They unite with the radial systems by offshoots of tubes, 

 and it is evident that at the surface of the body most of the interradial tubes open directly 

 outwards. 



There is no very definite relation between the outward opening of the tubes within and 

 the eminences and interspaces ; moreover, the pores are situated without order. 



The majority of the tubes are nearly 3^ inch in diameter, some being 5^ inch, but 

 very small tubes are rare. 



The fossilization of the interior of the body has led to radiating portions being infiltrated 

 with a denser semi-granular calcite which hides much structure, and especially centrally. 

 In some places the tubes are filled with opaque matter, and the intertubular spaces are 

 readily distinguished, whilst in others the intertubular spaces are large, and the tube has 

 either disappeared or remains in very transparent calcite. Under this condition, it is difficult 

 to distinguish tube from continuous infiltrated calcite in section. Relics of the pores, as clear 

 spaces, are to be seen in radial sections, The height of the body is 2n, inches, and the whole 

 resembles a Parkeria. 



SYBINGOSPH^RIA PLA.NA, Duncan. 



The body is oblately spheroidal, almost smooth, on the surface, with many minute 

 granules on it, and numerous small shallow scattered pores. The granules are flat, with 

 rounded, or elongate, or irregular bases, and are about the same size as the pores. Many tubes 

 open on them, forming circles on their periphery, and also into the pores, and there is con- 

 siderable variation in their caliber. No tube reticulation exists on the surface, but the 

 massing of the tubes is closer in some places than in others. 



In radial sections of the body a very marked tube arrangement is to.be seen. A very 

 considerable number of long, narrow, radial series pass on all sides to the surface, bounded 



