JAPANESE MOLLUSKS, FISSURELLID^.. 107 



Not Humphreys and DaCosta, Conch., p], 7, f. 3. 



Not Fissurella macrosehisma Sowerby, Genera of Shells, Fiss., f. 

 5, =J/. hiidula Swains. 



Not Fissurella macrosehisma Sowb., Conch. Illustr., f. 39. 



Not Macrocldsma maxima Sowb., Thes. Conch., Ill, pi. 244, f. 

 216, 217. 



The prominent specific characters of this form are its very large 

 perforation which is siidde'nly dilated postenorly to double the width 

 of its middle portion. The anterior part of the shell has several 

 carinpe. In M. hiatula Sw., the hole is not thus dilated posteriorly, 

 nor is it so in the various figures of Humphreys and Sowerby 

 referred to above. Chemnitz reports the species from Japan. 



Macrosehisma sinensis A. Adams. PI. VI, figs. 6, 7, 8. 

 Pilsbry, Manual of Coneh., XII, p. 190, pi. 59, f. 56-59. 



Tabu-Shima (Ad.) ; Neraoto, Boshiu (Stearns, twelve specimens). 



Shell oblong, the length slightly exceeding twice the breadth ; 

 lateral margins slightly convex, subparallel, anterior margin well 

 rounded, posterior margin more or less truncate, often emarginate. 

 Anterior slope straight or slightly convex, more than half the length 

 of the shell ; side slopes straight. 



Surface sculptured with close, fine radial stride, latticed by con- 

 centric raised strife, which are much less obvious on old than on 

 young shells; the anterior portion having about four very inconspic- 

 uous low radial ridges. Color either (1) dotted, speckled and ob- 

 scurely banded with black on a pale huffish ground, or (2) blackish 

 at the sides, crimson in front and behind, or (3) crimson throughout, 

 with some faint blackish rays. Posterior slope very short, about 

 equalling the length of the eroded portion behind the hole ; gen- 

 erally concave, or broadly guttered behind the hole. Perfora- 

 tion wedge-shaped, with nearly straight sides, gradually diverging 

 backward; very narrow in front, the back margin rounded, with 

 an eroded tract behind it. Length of hole slightly less than one-third 

 the entire length of the shell. Interior white with a bluish stain ; 

 hole-callus well marked, its edge stained with olive-black at the 

 sides. Peristome strongly curved upward behind, much less so in 

 front, the lateral margins nearly level. 



Length 23 i, breadth lOs, alt. 6 mm. 



Length 23^, breadth 10s, alt. 6t mm. 



Length 21, breadth 9s, alt. 6 mm. 



This species differs from M. macrosehisma in the form of the per- 

 foration, which is wider posteriorly but not abruptly dilated there. 



