29g mazatlan univalves 



Family CAPULID^. 



Genus HIPP ONYX, Defr. 



Cochlolepas, mein. 1753 —K. Sf A. Ad. Gen. vol. i. p. 373. 

 (Non Concliolepas, Lam.) 



346. HlPFONYX SEEEATTTS, n. S. 



M. t. conicd seu depressa, alba, ; apice decoUato, sitbcentrali 

 seu valde remoto, interdum valde prominente j lamellis crehris, 

 acutis, exiantihus, basi parallelibus, concentrice ornatd ; apieem 

 versus radiatim costatx ; supra lamellas radiatim tcnuissime 

 sulcata ; basi latissimd, planata, lamellis creberrimis instructa ; 

 lamellis profaade serratis, lobis subquadratis ; inter lamell-as 

 epidermide fused copiosissime indutd, tceniis incisis confertd ; 

 cicatrice musculari traasversim corrugatd. 

 Proc. Zool. Soc. 1856, p. 3. no. 2. 

 .P= Hipponyx foliaceu3, Mice, in Zeit. f. Mai. 1851, p. 36, 



no. 129, non Cluoy Sf Gaim. 



This well marked species differs from H. antiqnata, Linn. 

 in the ckaracter of the base, wliich is broad and flat, made up 

 of very numerous, close-set lamellae, deeply serrated into large 

 scarcely rounded lob?s. The interstices are filled with epider- 

 mis, in irregular ribband-like shreds as in Byssoarca Pacifica. 

 The exterior, which rarely displays its characters satisfactorily, 

 has slight tubercular ribs near the apex, which are continued 

 over the lamellae as very fine, rather distant, indented striae. 

 The apex is sometimes flat, sometimes high and curved back 

 as in Emarginula rosea. It is always decollated and eroded. 

 One extremely young specimen has the minute helicoid apex 

 adhering to the spreading, rounded shell. The shelly base is 

 almost always very thin and smooth, sometimes scarcely per- 

 ceptible. It is nearly related to an Australian species, probably 

 H. foliaceus, Q>.io// ; but in that species the lamelhe are serrated 

 outside with the strong radiating sulci ; the lobes of the basal 

 laminae are more roundod ; and the epidermis is finer and 

 lighter. The largest specimen measures (from the very pro- 

 jecting apex) long. "96, lat. '9is, alt. •46. 

 A very flat sp. „ -86, „ "78, „ -25, 

 A very conical sp. „ 'OS, „ '73, „ '43. 



Hab. — Mazatlan ; gregarious, attached to each other, or on 

 shells, (Byssoarcse, &c.) rare ; L'pool Col. 



