THE VOYAGE OF H.M.S. CHALLENGER. 



H. — Cryptoidea. 



With double sutural laniinse. 



Cryptoconchus, Blainville. Gryptocliiton, Gray and Middendorff. 



Amicula, Gray. 



a. Amicula Dall, s.s. 



b. Chlamydochiton Dall. 



I.— Chitonelloidea. 



Tail plate funnel-shaped. Laminae thrown forward. 



Chitonellus, Blainville. CJwneplax, Carp. 



a. Cryptoplax, Gray. a. Chitoniscus, Carp. 



