346 



rounded ; marginal line straight, deeply sinuated in front ; dorsal 

 valve slightly produced, very obtuse ; with a large incomplete per- 

 foration ; cardinal area small, linear ; deltidia small, nearly trian- 

 gular, central keel broad, large and rounded ; ventral valve rather 

 broad posteriorly, its posterior margin nearly straight ; with a 

 large, broad and rounded ventral groove ; internal appendages as 

 in T. rubra ; margin of the valves very slightly crenulated. 



Brought from Natal by Dr. Krauss ; a comparison with the 

 Lamarckian specimen has proved this to be his T. Pisum ; it has 

 nevertheless been described under the name of T. Natalensis by 

 Kuster. Also found at Sydney by Mr. Jukes. 



8. Terebratula cognata (pi. lxviii. f. 12, 13, 14.) Chemn. 

 vol. viii. pi. 78. f. 688, a,b. 



Testa subtrapezoidali, antic! rotundata, pallescente, nonnunquam 

 rubente ; valvis insequalibus, radiatim obsolete striatis, striis versus 

 marginem obliteratis ; linea marginali lateraliter antice-que flexuosa, 

 valva dorsali convexa, lira mediana inconspicua ; apice subacumi- 

 nato, reflexo, foramiue rnagno, haud integro, area cardinali angusta, 

 fleltidiis parvis, trigonalibus ; valva ventrali planulata, margine 

 postico rectiusculo, sulco mediano subperspicuo, ossiculo interno 

 ramulos duos centrales divergentes, ad apices expansos sistente ; 

 margine interno valvarum denticulate 



Shell nearly trapezoidal, rounded in front, of a pale colour, some- 

 times reddish ; valves unequal, obsoletely radiately striated, the 

 striae entirely obliterated near the margin ; marginal line fiexuous 

 in front and on the sides ; dorsal valve convex, with an inconspicu- 

 ous central ridge, its apex somewhat acuminated, reflected, with a 

 large incomplete perforation ; cardinal area narrow, deltidia small, 

 triangular ; ventral valve flattened, its posterior margin nearly 

 straight, with a scarcely evident central furrow; internal appen- 

 dages consisting of two little central diverging branches, expanded 

 at their apices ; margin of the valves denticulated within. 



We have two varieties in colour ; from South Africa, according 

 to the late G. Humphrey. 



I). Terebeatula dorsata (pi. lxviii. f. 15, 16, 17.) Lam. 



Testa suborbiculato-trapezoidali, gibbosa, albicante, valvis inae- 

 qualibus, radiatim liratis, linea marginali flexuosa; valva dorsali 

 postice subacuminata, reflexa, truncata, carina mediana lata, obtusa, 

 foramine mediocri, haud integro ; area cardinali magna, lata, sub- 

 planulata, deltidiis parvis, trigonalibus ; valva ventrali subtrigonali, 

 apice subacuto, marginibus posticis declivibus, sidco mediano lato 

 subperspicuo, ossiculo interno magno, f testge longitudinis, postice 



