58 MolL 
MOLLUSCA. 
mediterraneus (Gray, Reeve) ; fmtivus (Monter., 1872) ; ;polii (Philippi) 
= cinereus (Poli) =; cremilatus (Risso) = caprearum (Scacchi) = euphm 
(Costa) = decipiens (Tiberi) ; minimus (Monter., 1878), Palermo ; pachy- 
lasmce (Monter., 1878), Messina, on Pacliylasma giganteum ; algesirensis 
(Capellini) ; caietanus (Poli) ; Icbvis, var. dories (Capell.), stigma (Costa) 
is the young state of it j Acanthopleura hanleyi (Thomps., Jeffr.) ; 
Acanthochestes fascicularis (L., Jeffr.) ; A, discrepans (Browne, Jeffr.) 
= fascicularis (Phil.) ; A. census (Risso). Giorn. Sc, Palerm. xiv. 
pp. 9-21, 
Chcstoplsura (Shuttl., H. & A. Ad. pt.): type, Chiton per uviamis (Lam.), 
Ch. hartivegi and nuttalli (Coop.), Alaska ; Dali, 1. c. pp. 111 & 112 ; 
radula, pi. i. fig. 10. 
Leptochiton cancellatus (Sow.) = asellus (Middend.) = alveolus (Jeffr.), 
Seas of Northern Europe, Alaska, Unalaska, and Sitka, and helhnapi 
(Dali, 1878), N. Pacific, 63° N. lat., 1006 fath., and also Kerguelen, 20-60 
fath., compared with alveolus (Sars, Loven) and some other allied species ; 
Dali, 1. c. pp. 97-99 ; radula of the first, pi. i. fig. 1. 
Deshayesiella (Carp., MS.), subg. n. of Leptochiton : no insertion plates, 
only sutural plates ; for L. curvatus (Carp^). Id. 1. c. p. 96. 
Trachydermon ruler (L.) = Icevis (Loven), Alaska and Arctic, T. alius 
(L.) = aselloides (Lowe) = sagrinatus (Couth.), Arctic and boreal, south 
to the Shumagin Islands ; id. 1. c. pp. 101-104, radula pi. i. figs. 3 & 4. 
Trachyradsia (Carp., MS.), subg. n. of Trachydermon^ central valves 
with two or more clefts ; type. Chiton fulgetrum (Reeve), and also T. 
aleutica (Dali, 1878), Western Aleutian Islands; id. 1. c. p. 105. 
Tonicella marmorea (Fabr.), Aleutian Islands and Arctic Seas, lineata 
(Wood), from Behring Strait to Japan and Monterey, and saccharina 
(Dali, 1878), Aleutian and Shumagin Islands; id. 1. c. pp. 106-109, radula, 
pi. i. figs. 5-7. 
Schizoplax (Dali, 1878),' Irandti (Midd.), Aleutian Islands to Sitka ; 
id. 1. c. p. 110, radula, pi. i. fig. 8. 
Maugerella (Carp., MS.), for M. conspicua (Carp.), California, radula; 
«V/. Z. c. p. 78, pi. ii. fig. 11. 
Jschnochiton (Gray, 1847) = Lepidopleurus (H. & A. Ad.), type Chiton 
longicymla (Q. & G.). Dali (from Carpenter’s MS.), 1. c. pp. 112-114, & 
78, 79, distinguishes the following subgenera : — 
Stenoplax (n.) ; body elongate, scales elongate, chaff-like, striated, 
irregular, crowded. C. limneeiformis (Sow.), radula, pi. ii. fig. 13. 
Stenoradsia (u.) ; like Stenoplax, with numerous side slits. C. magda- 
lenensis (Hinds), radula, pi. ii. fig. 12. 
Ischnoplax (n.) ; occasional large scales rising above the rest, and very 
many short striated bristles ; mucro raised, subposterior. C'. pectinatus 
(Sow.), radula, pi. iii. fig. 23. 
Heterozona (n.) ; body elongate ; two kinds of rather solid, striated 
scales. II . cariosa (Carp., MS.), California. 
Ischnochiton (restricted) ; scales transverse, flattened, somewhat imbri- 
cated, generally striated. C. longicymla (Q. & G.), I. inter structus 
(Gould), regularis and cooperi (Carp.), radula, pi. ii. figs. 14, 15, 16. 
Ischnoradsia (Shuttl. pt.. Carp.) ; scales striated ; central valves, with 
