1894.] NATURAIv SCIENCES OF PHII.ADEIjPHI A. 71 



Family ISCHNOCHITONIDiE. 

 Genus CALLOCHITON Gray. 



Callochiton platessa (ioiild. 



Port Jackson. This is the Leptorhiton versicolor Ad. , of Angas' 

 list. It is a lovely shell of the most l)rilliaiit orange- red color. A 

 larger, dark-brown species allied to this, occurs on the Tasmaniau 

 coast, Callochiton ( Trachyradsia) iiwrnaf us Ten. -Woods. 



Genus ISCHNOCHITON Gray. 



The general arrangement of the species of this genus is fai- fioni 

 satisfactorv. Former classifications have been founded too exclusively 

 upon the girdle scales. The Australian species fall into five natural 

 groups, or sections, which may l)e defined as follows: — 



1. Iscluiovhlton s. str: type longlcymba Q. & G. 



Intermediate valves having 1-1 slits; lateral areas radially 

 sculptured, central areas finely granulated in quiucunx, or 

 longitudinally lirulate at the sides, with "V" sculpture 

 along the ridge. Girdle scales subequal, striated. 



2. ISteaoch'don : type jaloides A. & A. 



Animal much elongated: intermediate valves having several 

 slits on each side. 



3. Heterozoiia: type cariosa Cpr. 



Like IscJmochlton (sensu stricto), but girdle scales minute and 

 large, intermingled. 



4. Huplojilax now.: type smaragd in ks Aug. 



Intermediate valves having 1-1 slits; entire surface smooth 

 except for minute granulation; girdle scales convex, smooth. 



5. hvhiioradskc type aiidralis Sowb. 



Shell not unusually elongated; intermediate valves with 

 several side-slits, sculpture coarse; girdle scales very convex, 

 not striated. 



Ischnochitou Haddoni I'ilshry. 



Very abundant at Port Jackson and Port Hacking. This shouhl 

 be com|)areil with the type of Chiton crispus Reeve, Conch. Icon. pi. 

 19, fig. 120, a species I have not seen. Also with C. pallidns 

 Reeve, I. c. pi. IH, fig. 92. 



It is certain that this is not Chiton longicymba Blainville, 



