1 64 



The radial striae are rounded and fine, being separated from each other " 

 by spaces of about the same width. Three striae and two interspaces occupy 

 a space of 3 mm. along the front margin. 



Remarks : — In the fossil now being considered, the dorsal valve is so- 

 strongly convex that on viewing it anteriorly, posteriorly, or laterally, it looks 

 like a hemispherical body, the length and the width not being very widely 

 different. The ventral valve, on the other hand, is very low and is a little- 

 convex in the neighbourhood of the beak. It is concave along the margin 

 excepting the hinge-line. The concavity is somewhat less conspicuous along 

 the anterior margin, where there is a very gentle upfolding. 



These are the points that separate the variety from the type species of 

 Linnaeus. On this point Frech very appropriately observes, " Die unge- 

 wohnliche Dicke der kleinen Schale sowie die fliigelartige Verbreitung an der 

 Schlosslinie gestatten vielleicht die Beibehaltung des KAVSER'schen Namens - 

 als Bezeichnung einer Varietiit der Atrypa reticularis!' 



Nevertheless there is an Atrypa reticularis which has a very high dorsal ' 

 valve — almost as high as this variety. It is that which was described and 

 figured quite recently by Maynard from the New Scotland Formation (Lower 

 Devonian) of New York.** In it, however, the ventral valve is not that of the 

 Chinese variety, but has the habitus of the type species. Hence, both valves 

 taken together, the American example must be considered as an extra- 

 ordinarily thick variation of the species, if it is not a constantly ' thicker form. . 

 Otherwise, it might be called a variety of A. reticararis LIn., especially whfeit- 

 the thickness of the form is considered in correlation with its geological 

 antiquity. 



Localities: — -l) Ning-chang, Han-chung-fu, prov. Shen-hsi. 



Von Richthofen collected the original examples at Lung-tung-pei in ther 

 north-eastern border of the province of Sze-chuan. It is, however, doubtful 

 whether he really got the material at that place as Kavser seems to have be- 

 lieved. In the second volume of his China, Richtofen remarks, " Man ver- 

 kauft hier (Lung-tung-pei) devonische Brachiopoden, welchen eine besondere 

 Heilkraft zugeschrieben wird.^* " The writer supposes that the specimens- 



1) Maryland Geol. Survey, Lower Devonian, p. 392, pi. LXVII., figs. 26-28. 1913. 



2) China, vol. II., 599. 



