34 SVKIAX MOLLUSCAN FOSSILS. 



sive bent raised lines, which indicate in the progressive growth of the shell 

 the presence of a shallow notch at the edge of the aperture, corresponding 

 on a small scale with the fissure of Pleurotomaria. These markings are very 

 like those which have given name to the palaeozoic genus Raphistoma Hall 

 (Palaeontology of New York, I, p. 28, 1847). Coll. Bird. 



LocaUty and Position. — Abeih ; from an arenaceous portion of the Turo- 

 nian yellow marl. 



Colostracon curtum, sp. nov. 



Plate III, figs. 4 a, b, c, il. 



Testa inverso-conica, longior quam lalior, spira fere plana, ab anfmctus ultimi 

 parte interiori usque ad centrum minime concavus ; anfractus quatuor vet quinque 

 centrum versus ampliiudine citius decrescenies ; ultimi lateribus plants ante angulum 

 parum constiictis : apertura recta, angustiuscula, antice latior : superficies postice 

 striis minutis fiuctuosis, antice sulci* exiguis cincta; laln-urn simplex, tenuissimum; 

 labium anguste a<- tenuiter reflexum ; columella leviter rimulata. 



Shell inversely conical, longer than wide, spire almost plane, very slightly 

 concave from the inner side of the last volution to the centre : whorls four 

 or five, rather rapidly diminishing in thickness towards the centre, hav- 

 ing the sides flat and very slightly constricted just before the angle : 

 aperture straight, rather narrow, wider in front : surface encircled behind 

 with minute wavy stria?, before with light grooves; outer lip simple, very 

 thin ; inner lip narrowly and thinly spread upon the columella, which is 

 slightly fissured. 



Single specimen. Length, 17 mm., originally about 20 mm. ; width 

 ]2 mm. 



In the specimen from which the foregoing description is drawn, the 

 surface is spirally marked behind with minute wavy striae, and in front 

 liv rather wide shallow grooves. Between the two extremities the shell is 

 corroded, hut shows traces of lines intermediate in character between those 

 of the anterior and posterior parts, indicating that the whole exterior was 

 originally covered with revolving lines which became anteriorly wider and 

 deeper. It seems probable thai in its perfect state the front was produced 

 into an lo-like beak, as in the last species. Coll. Bird. 



Locality and Position. — Abeih j from an arenaceous portion of the Turo- 

 nian yellow marl. 



