124 MAZATLAN BIVALVES 



Murex princeps. The youngest specimen measures '05 in 

 length. A large specimen in Dr. Gould's collection, (locality 

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

 dermis) long. '62, lat. '28, alt. "25. 



A long, narrow sp. '15, '06, '06. 



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

 Hob. Gallapagos, Cuming. Mazatlan ; in Spondylus calcifer, 



and burrowing in Murex regius, very rare ; Lpool & Havre 



Coll. 



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

 and adult, of which one displays concentric ridges of growth, 

 like Crepidula Lessonii. 



GENUS LITHOPHAGUS, Megerle. 



Lithophagus, Megerle von MuJilf. 1811, JEnttv. p. 69 : Phil. 

 Handb. Conch, p. 363: DTcr. Com. Sept. et Dreis. p. 2 Lith- 

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

 Lam. 



173. LITHOPHAGUS ATTENUATUS, Desk. 



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



no. 25. Hani. L>escr. Cat. p. 238. 

 Lithodomus caudigerus, var., Sow. G-en. f. 3. five. pi. 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 long. 4 '7, 

 lat. 1'4, alt. *96. 

 Hob Peru, Chili, in stones, Deshayes. Mazatlan ; extremely 



rare, burrowing in Spondylus calcifer, Imperator olivaceus, 



and Murex princeps ; L'pool &f 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 dor so valde angulata ; umboni- 

 bus appressis, inconspicuis ; parte anticd tumida ; margin* 



