OF MOLLT7!?K'? FHOM MAZ.Vri.AV. ^75 



701. ? VlTRINELLA, Sp. iofl. 



Tablet 2535 contains » fragment, 'OSo across, of wliat wai pro- 

 bably a gigantic species of this genus or of Cyclotrema^ strong'? 

 keeled. 



492, DiALA PAUPERCULA, C. B, Ad. 



^=-Cingula paupercula, C. B.Ad. Pan, Shells, no. ; dia<jtiosi' 



mutata. 



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



D. t. nitida, solid a ; vert. nucl. arifr. iv., lirulis spii'alibus et 

 radiantihus tenuiter decussato ; t. adtdta decoUata, ve.'tice 

 mamillato ; anfr. norm. iv. ,• j)erifremate continuo ; bast obtuse 

 angidata, lacuna umbilicali a labia separata formata. 



Long. '085, long, spirse "OoS, 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 INIazatlan 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 " Cing^da,'" since that was 

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

 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 , 

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

 rimis, circa basim continuis ; lubrol . . . \^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 

 u.mbilicated. 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, v liite. 

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

 other smaller keels, decussated by radiating rugee. This mode of 

 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. MtrCRONALlA INVOLUTA, n. sp. 



M. t. parva, temii, albida, irregtdari, marginibns spine valdt 

 excurvatis ; vertice derln"> ; a-»f. norm. vi. -j-. . . . satis excur^ 

 259 



