124 5IAZATLAN BIVALVES 



Murex priuccps. The younfrest specimeu measures "05 in 

 length. A Large specimeu in Dr. Gould's collection, (locality 

 not recorded) measures (without taking into account the epi- 

 dermis) „ long. "62, led. "28, alt. '25. 



A long, narrow sp. „ "15, „ "06, „ "Oe. 



A short, transverse sp. ,, '18, ,, *14, ,, "12. 



Hah. — Gallapagos, Cuming. — Mazatlan ; in Spondylus calcifer, 



and burrowing in Murex regius, very rare ; L'pool Sf Savre 



Coll. 



Tablet 566 contains 3 sp. very young. — 567, 3 do. adolescent 

 and adult, of which one display's concentric ridges of growth, 

 like Crepidula Lessonii. 



Genus LITHOPHAGUS, Megerle. 



Lithophagus, Megerle von Miiltlf. 1811, JEntw. p. 69 -.—PUl. 

 Handh. Conch, p. 363:— D/^-r. Com. Sept. et Dreis. p. 2.— Lith- 

 odomus, Cuv. 1817, Regne Anim. vol. iii. p. 136. — Modiola, sp. 

 Lam. 



173. Lithophagus atteni^atus, Desk. 



Modiola attenuata, Desk, in Lam. An. s. Vert. vol. \\i. p. 28, 



no. 25. Hani. Descr. Cat. p. 238. 

 Lithodomus caudigerus, var., Sow. Gen. f. 3. — Rve. pi. 99, f. 3. 



Known by its greatly produced, slender form, and by the 

 incnisting beaks, which are appressed, smooth, closed exter- 

 nally, but hollowed in the whole inner surface. Master 

 Archer found a very large specimen, measuring long. 4" 7, 

 lat. 1-4, alt. -96. 

 Hah. — Peru, Chili, in stones, Deshayes. — Mazatlan ; extremely 



rare, buiTOwiug in Spondjlus calcifer, Imperator olivaceus, 



and Murex princeps ; L'pool Sf 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. — 570, a drawing of 

 Mr. Archer's specimen, by Master John Jackson. 



174. Lithophagus calyculatus, n. s. 



L. t. tumidiore, curtd, in dorso valde angulaid ; umboni- 

 bus apprcssis, inconspicuis ; parte' anticd iumidd ; margine 



