179 



popular example is found in Spirifericlac. In this family Schuchekt^' proposed 

 a Subgenus Spiriferinae beside the other two Reticulariae Waagen and Marti- 

 niinae Waagicx. The last sub-famil)- is " with a smooth surface," while Reti- 

 culariae is spinous on the surface. In the diagnosis of the first sub- 

 family nothing is said about the surface sculpture. From these examples 

 it is suggested that surface aculpture is in present palaeontolog}' not 

 regarded as so significant as shell structure. It is this course that the 

 writer has been led to follow in deciding the systematic position of these 

 peculiar Chinese Krachiopods. They are placed in the family of Athyridae, 

 and are to be named , Itliyrisiiia . 



The characteristics of the new genus have been made known in the fore- 

 going lines somewhat in detail but in a rather disjointed way. A generic 

 diagnosis therefore will now be given before entering into the description of 

 the species. 



Shells biconvex, ventral valve somewhat exceeding the other in gibbosity. 

 Length somewhat inferior to width, the outhne being transverselj' elliptical or 

 obtusely rhombic. Hinge-line short. Ventral valve most C(nivex in the um- 

 bonal region, and its beak obtuscl)' pointed and curved, slightly overhanging 

 the hinge-line ; it is truncated b\' a circular pedicle hole. At the top of the 

 beak begins a distinct median sinus, which is narrov.- but deep in the umbonal 

 region, but graduall}' widens anteriorly ending in a tongue-like prolongation of 

 the anterior margin. 1 )orsal valve has a median fold in correspondence with the 

 sinus of the opposite valve, and the anterior margin is strongly concave in the 

 middle to meet the tongue-like prolongation of the ventral valve. Dorsal 

 beak very low and crooked, so that it is hidden beneath that of the opposite 

 valve. A^entral area indistinguishable or but slightly developed. The sur- 

 face of both the valves is ornamented with coarse radial ribs that seldom in- 

 crease on the lateral portions. In the sinus or on the fold the ribs are 

 somewhat less distinct and less prominent ; intercalation and dichotomy lake 

 place here. There are usually man)' concentric but fluctuating growth lines 

 that are somewhat scaly or lamellar. The shell structure is imi)unctatc. The 

 spirals are laterally directed. 



Remarks : — As has alreadx' been stated, th's genus morpholc'gicall\- 



1 ) SCHI-CHKKI : Op. cit., f. 4IO-414. 



