342 CHITONID A. 
ISCHNOCHITON (restricted). Scales transverse, flattened, some- 
what imbricated, generally striated. 
ISCHNORADSIA, Cpr. (ex Shuttlew.). Scales striated; central 
valves with many slits. C. trifidus, Cpr. 
LEPIDOPLEURUS, Cpr. Scales solid, imbricated, smooth. C. 
Mertensii, Cpr. 
LEPIDORADSIA, Cpr. Similar to the last, with many slits in 
central valves. C. Australis, Sowb. 
STENOPLAX, Cpr. Body elongate; scales elongate, chaffy, 
striated, irregular and crowded. C. limaciformis, Sowb. 
(Ixxxv, 96). 
STENORADSIA, Cpr. Like Stenoplax, with numerous side-slits. 
C. Magdalensis, Hinds (1xxxv, 77). 
ISCHNOPLAX, Cpr. Like Stenoplax, but with occasional large 
scales rising above the rest, and a multitude of short striated 
bristles ; mucro raised, subposterior. 
HETEROZONA, Carpenter. Body elongate ; two kinds of rather 
solid, striated scales. 
CALLISTOCHITON, Cpr. Insertion-plates regular, branching 
middle valve with one, anterior and posterior. with many slits 
teeth excurved, plumate ; eaves projecting, long; sinus broad, 
shallow, laminate; girdle narrow, with small scales; oils 
encircling. 
. 
’ 
. 
] 
* * With girdle-pores. 
CALLISTOPLAX, Cpr. Shell as in Callistochiton, poriferous girdle 
naked. C. retusus, Sowb. (1xxxv, 78). 
ANGASIA, Cpr. (Hanleyia, Ad.and Angas, not Gray.) Shell like 
Cheetopleura, but the eaves small; girdle minutely squamulose- 
pilose, fasciculated at the sutures. A. tetrica, Cpr. 
NEWCOMBIA, Cpr. Insertion-plates regular, branching ; middle 
valve with one, anterior and posterior with many slits; teeth 
solid, not propped ; eaves short; sinus rounded, simple; girdle 
fleshy , with long, hairy bristles. 
CERATOZONA, Dall. Shell like Cheetopleura, but the teeth raised, 
eaves short ; sirdle smooth, fasciculated around the sutures and 
margin. This differs from all other hairy or spiny Chitons, at 
all nearly related to it, in the mantle-ornaments not being 
inserted into sockets, but being extensions of its surface. C. 
Guildingii, Reeve (Ixxxv, 19). 
PALLOCHITON, Dall. Like Nuttallina; zone downy; central 
lamin unifissured. This section unites in a form resembling 
Nuttallina,some of the features of Middendorfia, from which the 
girdle differs in being spongy and covered with soft hairs 
instead of short shelly bristles. O. lanuginosus, Cpr. 
C. Lophyroidea. 
Insertion-plates broad, pectinated, projecting backward. 
