1901.] NATURAL SCIENCES OF PHILADELPHIA. 203 



distinct, impressed. Edge beveled, having a narrow gray or green- 

 ish border and profusely or sparingly dotted with black -brown. 



Length 12, breadth 10, alt. 4.5 mm. 



Length 13, breadth 10.5, alt. 4.5 mm. 



Loo Choo Islands (Mr. Y. Hirase). 



A small species with inconspicuous sculpture, but so solid that I 

 take the specimens to be adult. The base is curved in some speci- 

 mens, as though they had lived on shells, while in others it is 

 nearly level. None of the species described from the region 

 resembles this one. 



CHITONIDJE. 

 Onithochiton Hirasei n. sp. 



Oblong, moderately elevated, not carinate, the dorsal ridge 

 being rounded, side slopes straight; smooth and glossy, yellow 

 marbled with whitish, having a chestnut triangle or some chestnut 

 dots at the ridge of each valve, several blue and olive clouds or 

 blotches in front of the diagonal lines, and with more or less 

 variegation of the same colors on the lateral areas. 



Anterior valve having black eyes arranged in about 10 primary 

 radii, with many others irregularly scattered or in shorter rows. 

 Valve ii, as usual, longer than iii to viii; all intermediate valves 

 beaked, having the lateral areas indistinctly defined, the diagonal 

 ridge inconspicuous except near the beaks ; growth-lines fine, curv- 

 ing backward on the ridge; and adults have several spaced, deeper 

 concentric grooves near the sides and anterior margin of each 

 valve ; near the beaks the diagonal ridge becomes raised and beaded, 

 and there are irregular, forwardly -converging zigzag grooves upon the 

 pleural tracts. A narrow line of eyes radiates along the anterior 

 part of each lateral area; and there are pits as large as the eyes, 

 but not pigmented, scattered sparsely upon the pleural tracts. 

 Valve viii depressed, triangular, with the usual terminal apex, 

 and linear, rugose, posterior area; the breadth of the tegmentum 

 twice its length. 



Interior white, stained with dull purple and punctulate in the 

 middle; valve-callus heavy; reflexed border rather wide; sinus 

 rather wide, finely denticulate; insertion plates moderately long, 

 finely pectinated outside ; slits 9 in valve i, 1-1 in valves ii to vii ; 

 a wide, flat ledge in place of the insertion-plate in valve viii. 



