1865.] OF MOLLUSKS FROM WESTERN NORTH AMERICA. 281 
Long. *31, long. spir. ‘21, lat. ‘09; div. 12°. 
Hab. Acapulco, on Ostrea iridescens, Rowell. 
The spire-outlines are scythe-shaped. It is much larger and more 
solid than L. distorta and (?var.) yod. 
CERITHIOPSIS INTERCALARIS. 
C. t. valde elonyata, rufo-fusca, marginibus spire rectis, suturis 
impressis ; anfr. nucl. iii. +? . . . (decollatis), radiatim dis- 
tanter liratis ; norm. x., planatis; costis radiantibus primum 
xii., dein cire. xxil., angustis, haud extantibus, ad peripheriam 
continuis, interstitiis quadratis ; carinis spiralibus primum ii. 
nodulosis, dein alteris ii. minoribus inter eas intercalantibus ; 
carina postica suturali haud nodulosa, secunda valde nodulosa, 
tertia intercalante equante sed haud noiosa, quarta antica 
valde nodosa, quinta circa peripheriam, prime et tertie simili, 
haud nodosa, alteraque contigua, minima, inter quas sutura 
gyrat ; basi concava, levi; columella valde contorta; canali 
brevi, aperto; labrot... * 
Hab. Guacomayo. 
This beautiful species comes nearest to C. bimarginata, C. B. Ad., 
of which, indeed, the type does not agree with the diagnosis so well 
as does this specimen. It differs in having other spiral ribs inter- 
calating between the two principal ones, and in the radiating sculp- 
ture being continued to the periphery. One specimen only was 
found in the shell-washings, not perfect at the mouth. 
CoLUMBELLA HUMEROSA. 
C. t. parva, turrita, alba, linea seu maculorum serie fusca inter- 
dum spiram ascendente; marginibus spire parum excurvatis ; 
anfr. nucl.? . . . |detritis|; norm. vi., convexis, postice tumen- 
tibus, suturis valde impressis ; costis radiantibus vii.—viii., dis- 
tantibus, validissimis, rotundatis; interstitiis late undatis ; 
lirulis validis spiralibus extantibus, interstiliis eas equantibus, 
costas et harum interstitia transeuntibus ; basi angusta ; labro 
vx varicoso, postice emarginato, intus solidiore, dentibus circ. 
iv. munitis ; apertura late undata, compacta. 
Long. *26, long. spir. 15, lat. *13; div. 38°. 
Hab. Acapulco, on Ostrea iridescens, Rowell. 
The sculpture resembles that of Rhizocheilus, and the tall spire that 
of Anachis ; yet it appears to belong to the restricted typical genius. 
Mouricipra DUBIA, Var. SQUAMULATA. 
Variat ¢. omnino albida; sculptura tenuiore; spira elevata; tota 
superficie minute squamulata, sguamulis imbricatis. 
Hab. Cape St. Lucas (Xantus). 
The opercula in the beautiful specimens sent by Mr. Pease are 
* I forgot to measure the specimen before returning it to the Smithsonian 
Inst. ; but it is about the size of C. assimilata. 
