124 MAZATLAN BIVALVES 
Murex princeps. The youngest specimen measures ‘05 in 
length. A large specimenin Dr. Gould’s collection, (locality 
not recorded) measures (without taking into account the epi- 
dermis) ee long. °62, lat.°28, alt. °25. 
A long, narrow sp. eels. 206, ,, SOG: 
A short, transverse sp. bere tes reel, 3: i Ee 
Hab.—Gallapagos, Cuming—Mazatlan ; in Spondylus ealcifer, 
and burrowing in Murex regius, very rare; L’pool & Havre 
Coll. 
Tablet 566 contains 3 sp. very young.—567, 3 do. adolescent 
and adult, of which one displays concentric ridges of growth. 
hke Crepidula Lessonii. 
Genus LITHOPHAGUS, WMegerle. 
Lithophagus, Megerle von Mihlf. 1811, Entw. p. 69:—Phil. 
Handb. Conch. p.363:—Dkr. Com. Sept. et Dreis. p. 2.—Lith- 
odomus, Cuv. 1817, Regne Anim. vol. iii. p. 136.—Modiola, sp. 
Lam. 
173. LirHopHAGUs ATTENUATUS, Desh. 
Modiola attenuata, Desh. in Lam. An. s. Vert. vol. vu. p. 28, 
no. 25. Hanl. Descr. Cat. p. 238. 
Lithodomus caudigerus, var., Sow. Gen. f.3.—Rve. pl. 99, f. 3. 
Known by its greatly produced, slender form, and by the 
incrusting beaks, which are appressed, smooth, closed exter- 
nally, but hollowed in the whole inner surface. Master 
Archer found a very large specimen, measuring Jong. 4°7, 
lat.1°4, alt. °96. 
Hab.—Peru, Chili, in stones, Deshayes.—Mazatlan ; extremely 
rare, burrowing in Spondylus calcifer, Imperator olivaceus, 
and Murex princeps ; L’pool & Havre Coll. 
Tablet 568 contains a sp. of Imperator olivaceus, broken 
across, and displaying a young L. attenuatus, with L. arista- 
tus.—569, a very young sp. ‘13 in length—4570, a drawing of 
Mr. Archer’s specimen, by Master John Jackson. 
174. LitHOPHAGUS CALYCULATUS, 7. s. 
LL. t. tumidiore, curta, in dorso valde angulata ; umboni- 
bus appressis, inconspicuis ; parte antica twmidad ; margine 
