OF CONCHOLOGY. 
39 
study of thè type convinces me that it differs from norma! adult 
speciméns of peltoides only in being abnormally elevated, dead 
and faded. The siphon mark is evident under a glass. The 
epidermis is gone; and thè margin is irregular, showing that its 
station must bave heen unfavorable to luterai expansion, hence 
thè unusually elevated and conical form. 
The animai has not, as yet, been observed. For a littoral 
species it has an extraordinary range ; from Monterey to thè 
Gallapagos Islands, and its discovery at thè latter point by Dr. 
Hable is extremely interesting. The only other species known 
from Monterey and thè Gallapagos are Semele rupium, Sby.; 
{^)Modiola capax, Conrad; (ì)Bulla Quoyi, Gray ; and {J.)Pur- 
pura triangularis, Blainv. The three latter are doubtful. Two 
other species of Siphonaria [*S'. gigas and 8. scutellum{?Y\ are 
reported from thè Gallapagos. (The locality of 8 . scutelhim is 
given by Reeve as New Zealand.) 
The following species are known on thè West Coast, north of 
Panama: 
8iplionaria gigas, Sby., Equador to Gulf of California. 
8. lecanium, Phil., “ “ “ 
8. cliaracteristica, Reeve {^.-gigas var.), Gallapagos and Pan- 
ama. 
8. peltoides, Dall ex Cpr., Gallapagos to Monterey. 
8. seutellum, Blainv., Gallapagos. 
8. maura, Sby., Panama. 
8. pica, Sby., Panama and Cent. Am. 
8. costata, Sby., “ “ 
8. cequilirata (Reeve), Cpr., Gulf of California. 
8. (? var.) palmata, Cpr., Mazatlan. 
8. thersites, Cpr., Puget Sound to Sitka. 
There are probably severa! other species on thè coast and Gulf 
of California, which I cannot determine from thè material at 
hand. There are also one or two species in Japan, which may 
be found on some of thè Aleutian Islands. 
ANISOMYON, Meek, 1860. 
Anisomyon, Meek and Hayden, Amer. Journ. Sci. and Art, 
xxix (2d series), p. 33, pi. 1 {A. patelliformis), Jan., 1860. 
Type A. horealis, Morton sp. (as Hipponyx.) 
This genus was constituted for several rounded, thin, sparsely 
striated, cretaceous, patelliform shells, which bave thè muscular 
impression interrupted on thè right side, and thè apex, when 
perfect, subspirai or reflected. They appear to form a passage 
