OF MOLLT7SK3 FROM MAZATLAN, 372 



701. ? VITRINELLA, sp. ind. 



Tablet 2535 contains fragment, '085 across, of what wa* pro- 

 bably a gigantic species of this genus or of Cyclotrema, strong^ 

 keeled. 



492, DlALA PATJPERCULA, C. B. Ad. 



= Cingula paupercula, C. B.Ad. Pan. Shells, no. : diapxos* 



tnutata. 



= 10dostomia mamillata, Maz. Cat. no. 492 : diagnosi aucta. 



D. t. nitida, solida ; vert. nucL anfr. iv., lirulis spiralibus ei 

 radiantibus tenuiter decussato ; t. adulta decollata, vestice 

 mamillato ; anfr. norm, iv.; peritremate continue ; basi obtuse 

 angulata, lacuna umbilicaii a labio separata formata. 



Long. -085, long, spirse -055, lat. '05 ; div. 34. 



The fortunate discovery of a perfect young specimen and some 

 adult shells in the shell-washings of Professor Adams's collection 

 enables us to explain the anomalies described in the Mazatlan Cata- 

 logue, where the solitary dead shell was referred, with doubt, to 

 Odostomia, in consequence of its truncated apex. It was not pos- 

 sible to recognize in it Professor Adams's " Cingula" since that was 

 described as having the apex " subacute," and the angular base ant 1 

 continuous peritreme were not mentioned. The nuclear whorls are 

 sculptured as in Alaba supralirata ; but the vertex, instead of being 

 persistent as in that genus, appears to be always decollated in the 

 adult. The shell has the peculiar glossy texture of Diala. 



702. MANGELIA SULCATA, n. sp. 



M. t. subturrita, albida, apice obtuso ; anfr. vii., tumidioribus 9 

 liris vii., obtusis> rectis, vix angulatis ; sulcis spiralibis creber- 

 rimis, circa basim continuis ; labrol . . . \_fracto]. 



Long -2, long. sp. -12, lat. '07 ; div. 35. 



Hab. Mazatlan ; one specimen off Spondylus, on tablet 2538 j 

 Liverpool Collection, 



703. ? TORINIA, sp. in. 



Tablet 2539 contains a small shell, '035 across, consisting of 3| 

 smooth, flattened, sinistral whorls ; with a distinct suture, but not 

 umbilicated. In a larger specimen (unfortunately lost), under the 

 microscope this sinistral vertex appeared turned completely upside 

 down, with more than half a whorl of an orbicular shell, vhite. 

 sculptured like Vitrinella, with a very strong peripherical keel, and 

 other smaller keels, decussated by radiating rugae. This mode oi 

 growth is exactly as in the young Torinia ; but the adult must have 

 been very distinct from any known species, and perhaps did not 

 belong to any described genus. 



550. MUCRONALIA INVOLTJTA, n. Sp. 



M. t. parva, tenui, albida, irregular?, marginibus spirts valdt 

 KKCurvatis; vert ice dediv"' ; anf. norm. vi. +. . . . satis excur* 

 259 



