MACKOSCHISMA. 191 



Ish, obscurely showing the dark rays of the outer surface ; perfora- 

 tion margined by a narrow callus. 



Length 10* breadth 5, alt. 2i mill. 



Tabu-sima, Japan ; China Seas ; Singapore. 



M. sinensis A. Ad. P. Z. S. 1855, p. 122.— Sowb. Thes., p. 205, f. 

 219.— A. Ad. P. Z. S. 1867, p. 312, t. 19, f. 28 (animal.) 



A beautifully clathrate species, the concentric raised striae being 

 equally as elevated as the radials, but narrower. Some specimens 

 have only one pair of broad rays, the anterior pair being absent. 

 There is sometimes a pink tint on each side of the fissure. 



M. weldii Ten ison- Woods. PI. 59, figs. 33, 34, 35. 



Shell lengthened (the length a little exceeding twice the breadth), 

 elevated (the altitude contained about 4i times in the length) ; 

 lateral margins nearly straight, but a trifle convex ; surface finely 

 radiately ribbed, the riblets subequal, but occasional ones are a trifle 

 larger ; growth-lines fine, irregular. Perforation obtusely wedge 

 shaped, its length contained five times in the length of the shell. 

 Color grayish, closely speckled and suffused with black in more or 

 less distinct rays ; lighter around the edges. 



The peristome is strongly curved upward posteriorly, not at all 

 in front. About every fourth riblet of the outer surface is a trifle 

 larger than the others, but the difference in size is not notable. In- 

 side bluish-white. Fissure surrounded by a rather narrow callus 

 rim; muscle-impression not deeply impressed except posteriorly. 

 Fissure oblong-wedge-shaped, rounded at each end, its length a little 

 over twice its greatest width, excavated on the back margin. 



Length 201, width 9, alt. 43 mill. 



Circular Head, Tasmania. 



M. tasmanica Ten.-Woods, Proc. Roy. Soc. Tasm. for 1875, p. 157, 

 1876 (not if. tasmanice Sowb.). — M. iveldii T.-Woods, P. R. S. Tasm. 

 for 1876, p. 156, 1877 ; and var. rosea radiata, I. c. 



First described as M. tasmanica, the name changed on account of 

 the similarity to Sowerby's M. tasmanice. 



Var. roseoradiata Tenison-Woods. 



Ornamented with numerous rose colored rays. 

 M. Tasmania Sowerby Jr. PI. 59, figs. 52, 53, 54. 



Shell oblong, the length double the breadth or nearly so, elevated, 

 the altitude one-fourth to one-third the length ; lateral margins 



