204 PROCEEDINGS OF THE ACADEMY OF [Maroll, 



Girdle dark brown Avith irregular buff patches, smooth to the 

 eye, but seen to be microscopically granulose under a strong lens. 



Length about 36, width 20 mm. 



Hirado, prov. Hizen. Types Xo. 80,571, coll. A, N. S. P., 

 from No. 1,176 of Mr, Hirase's catalogue. 



This is the first species of the genus described since the publica- 

 tion of my monograph in 1892, and the only one known from 

 north of the equator. The sculpture of the valves is unlike any 

 described Onithochiton. A very young specimen was reported as 

 " Tonicia sp. " in the JVautilus, XII, p. 50. 



It is named in honor of my esteemed Japanese correspondent. 



CRYPTOPL ACID^ . 



Two species of Cryptoplax, the first known from north of the 

 equator, have been found by Mr. Hirase, at Hirado, Hizeu. One 

 of them, which I call C. japonicus n. sp., has valve- sculpture like 

 C. Gunnii (Rve. ) of South Australia, and the spacing of the 

 valves along the back is similar; but in the Japanese species the 

 last four valves are smaller, valve viii being scarcely longer than 

 valve ii, while in C. Gunnii and G. striatus it is a fourth longer. 

 The girdle is densely spiculose, much as in C. striatus. The articu- 

 lamenta are green. 



Length of dried animal about 26, breadth 5.5 mm. 



In another species, C. rhodoplax n. sp. , the valves are spaced 

 about as in C. japonicus, but are sculptured much as in C. larvce- 

 formis, with low, irregular ridges jDarallel to the lateral margins of 

 the valves, the articulamenta being bright rose colored. Valve vi 

 is the smallest. The posterior insertion-plate of valve viii is vertical ; 

 and the sutural laminte and insertion-plates of all the valves are 

 much shorter than in C. larvceformis. 



Length of the dried animal 28 mm. 



A full account of these species will be given later; and mean- 

 time I hope to procure alcoholic specimens for description and illus- 

 tration, 



PBTRIOOLID^. 

 Petricola cyclus n. sp. 



Shell solid, white, subcircular though with somewhat irregular 

 outline, swollen, the beaks full, projecting, turned forward, situ- 

 ated at about the anterior third of the length. Periphery convex 



