248 MAZATLAN UNIVALVES 



Hab. — Mazatlan ; extremely rare, on Chama and Spondylus ; 



L'pool Col. 



Tablet 1163 contains the perfect specimen. 



Genus PLIOTIA, Gray, 



Syn. B. M. 1840.— S". Sf A. Ad. Gen. vol. i. p. 404.— PAiZ. 



Sandb. Conch, p. 206. 

 Delphinula, pars, auct. 



The following shells are ranked doubtfully with this genus, 

 not having the expanded Hp of the typical species, and the 

 opercula being unknown. 



313. P LlOTIA CAEINATA, n. S. 



?L. t. solidd, cinered, rufo tinctd ; spird depressd, anfraciihus 

 iv. supra suhplanatis, suturd distinctd, angulata ; carinis iv. 

 extantibus circa peripheriam ; liris spiralibus iii. iw spird, 

 noduhsis ; u\. in basi r'otundatd, haud extantibits ; circa urn- 

 bilicum magnum radiatim rugoso-nodosd ; aperturd intus circu- 

 lari, anfr. penult, parum attingente ; anfractu ultimo valde 

 deeumbente. 



Shell comparatively solid and opaque ; it may be young, but 

 from the small size of the nuclear portion and the sudden 

 declension of the last whirl, it is presumed to be nearly mature. 

 Long. '03, lat. '045 by '04, div. (anfr. penidt.) 175°. 



Hab. — Mazatlan ; 1 sp. on Spondylus ; L'pool Col. 



Tablet 116-1 contains the specimen, 



314. PLiOTIA STBIULATA, n. S. 



?L. t. turbinlformi, spird subelevatd, alhidd, solidd; anfracti- 

 bus iii. rotundatis, radiatim exillimc ct coi\fertissime striulatis, 

 carinis parum extantibus iii. spiralibus ; iimbilico magno ; in 

 basi interdum rugis radianiibus ; aperturd declivi, solidissimd, 

 intus rotundatd, avfr. penult, parum attingente. 



The thickness of this little shell is extraordinary, being at 

 the posterior portion of the apertiire nearly "005 in. The 

 whirls are rounded, obscurely cariuated, and most minutely 

 and closely striated in the direction of growth. Long. "027, 

 lat. -037 by 03, div. 130". 



