OF MOLi.rsK'? rnoM MA2.vn.;.M. ^75 



701. ? VlTRINELLA, Sp. inO. 



Tablet 2535 contains » fragment, "085 acros«, of what wa* jYro- 

 bably a gigantic species of this genus or of Cyclotrema^ strong-j 

 keeled. 



492. DiALA PAUPERCULA, C. B. Ad. 



^=Cin(jula paupercula, C. B. Ad. Pan. Shells, no. : diagnon 



mutata. 



=^.Odostomia mamillata, Maz. Cat. no. 492: diagnosi aueia, 



D. t. nitida, solida ; vert. nucl. anfr. iv., lirulis spira/iOits et 

 rudiaiitibvs tenuiter deciissuto ; t. adulta decollatu, ve.-tice 

 maniillato ; anfr. norm. iv. ,- perifremate continuo ; Lasi obtuse 

 angulata, lacuna lunbiiicali a labio separuto formuta. 



Long. -085, long, spirae 055, lat. '05 ; div. '6A^. 



The fortunate discovery of a jierfect young specimen and some 

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

 enables us to exjilain the louialies described in the Mazatlan Cata- 

 logue, where the solit. lead shell was referred, with doubi, to 

 Odostomia, in consequei.-j 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 an»' 

 continuous peritreme were not mentioned. The nuclear whorls are 

 sculptured as in Alaha svpraUrata ; 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 ; anjr. vii., tumid ioribus ^ 

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

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



Long. '2, long. sp. •12, lat. "07 ; div. 35°. 



Hab. Mazatlan ; one specimen off i<pond)jlus, on tablet 2538 ] 

 Liverpool Collection. 



703. ?ToRiNiA, sp. in. 



Tai)let 2539 contains a small shell, "035 across, consisting of 3| 

 smoo'di, flattened, sinistral whorls; with a distinct suture, but not 

 wmbilicated. In a larger specimen (unfortunately lost), under tiie 

 inicro.->cope this sinistral vertex appeared turned completely upside 

 down, with more than half a whorl of an orbicular shell, v hitCi 

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

 other smaller keels, decussated by radiating rugie. Tiiis UKide 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. MuCRONALlA INVOLUTA, n. Sp. 



M. t. parca, tenui, albida, irregularis tnarginibus spirce valde 

 fjccurcatis s vertice de'lir': an/, norm. vi. +. . . .saiis excur- 



259 



