274 POLYPLACOPHORA OF LoRD HOWE AND NORFOLK ISLANDS, 



straight and set closer together, l>ecoming increasingly concave 

 to the axis as they recede. 



Girdle narrow, beset with minute scales. 



Length i-i) mm., breadth 2-5 mm. 



Station. — On the under side of smooth stones. 



Habitat. — Lord Howe Lsland. 



Remarks. — This shell is rare and local, only one small colony 

 of 5 or 6 specimens being taken on a piece of basalt shingle in 

 an open channel in the rocks at Ned's Beach, on the eastern side 

 of the Island. It is unlike any of the Australian or New Zealand 

 species of the genus, and is remarkable for its prominent sculp- 

 ture, and the curious differentiation in the arrangement of 

 pustules on the posterior valve. 



Mr. Iredale took, on the Kermadecs, an undescribed species 

 related to this. 



3. ISCHNOCHITON INTERMEDIUS, n.Sp. 



(Plate xi., figs.3, 3a, 36, 3c.) 



Shell rather depressed. Colour variable, either a monochrome 

 of olive, ochraceous, cream, pale, or dark brown, or variegated 

 with these tints, frequently with a dark or pale doi'sal stripe. 



Anterior valve with numerous fine, irregular, radiating riblets. 



Posterior valve: mucro elevated, central, with radiating riblets 

 upon the posterior half, fewer and coarser than those of the 

 anterior valve; anterior half similar to the central area of the 

 median valves. 



Median valves: lateral areas with 4-fi faint irregular granular 

 riblets; central areas not differentiated from the jugal tract, 

 sculptured as in allied forms. 



Girdle densely clothed with minute scales. 



Interior blue, sinus broad and shallow; anterior val\e having 

 12, median 1-1, and posterior valve 12 slits. 



Length 19 mm., breadth 9 mm. 



Station. — On the under surface of loose stones in shallow water, 

 in sheltered pools. 



Habitat. -Norfolk Island. 



