120 
presso, cardinalibus valde accesso; dente cardinali secundo in 
valva sinistra latissimo, cuneiformi, sensim assurgente. 
Long. 57, alt. 53, crass. 26 mill. 
Hab. 2 
The Dosinia scalaris, Menke, is a very peculiar shell, and has 
affinities with three species, by which it is connected with other 
groups, at the first sight remote from it. One of these species is D. 
deshayesii of A. Adams; the second, from the Royal Museum at 
Stuttgardt, named by me D. affinis; the third is the above. The 
shape of this last is nearly the same as that of D. scalaris, but the 
sculpture is very different, consisting in D. ovalis of close-set rounded 
and not elevated strize, which at the sides do not change into lamelle. 
The greatest difference is expressed by the size and form of the pallial 
sinus, which in D. scalaris is very broad and moderately deep, in- 
closed by concave lines, and with a large rounded apex, whilst in 
D. ovalis it is very small and long, and considerably ascending. In 
the former, the second cardinal-tooth of the left valve is broad and 
thick ; in the latter it is wedge-shaped, and increases by degrees from 
the base to the very sharp and linear top. Accordingly, the last 
tooth in the right valve is very remote from the second, and both 
of them are separated by a broad triangular cavity. 
5. Dostn1A EBURNEA, Romer. D. testa cordato-orbiculari, tu- 
mida, diaphana, postice distincte angulata, antice rotundata, valde 
inequilaterali ; liris transversis, medio latis, planis, densis, ex- 
tremitates versus numero valde decrescentibus et in lamellis tenui- 
bus, sparsis, deorsum reflexis, postice elevatioribus, mutatis ; 
eburnea, nitidissima, zonis transversalibus pallidissime luteis 
ornata ; umbonibus tumidis, valde recurvis, longitudinem in ratione 
1:3 discludentibus ; margine ventrali regulariter arcuato, antice 
eximie adscendente, dorsali antico perbrevi, concavo, postico 
producto, curvato, oblique descendente ; lunula late cordata, im- 
pressissima, subplana; area lanceolata, subexcisa, sublevigata, 
lamellis brevibus, raris, e liris transversis excurrentibus, cincta ; 
ligamento subimmerso, conspicuo ; intus eburnea, nitida, disco opaco; 
sinu palliari mediocri, lingulato, in apice late rotundato, linea 
superiore horizontali ; dente lunulari crassissimo, dentibus cardi- 
nalibus tenuibus. 
Long. 37, alt. 34, crass. 20 mill. 
Hab. Insula Ceylon. 
In the middle of the shell the transverse striz are formed as in 
D. dunkeri, Phil.; they therefore produce the same shining aspect 
and interference of light, consisting in alternately bright and dark 
longitudinal traces. Near the posterior end these strize grow smaller 
and more elevated, till at last the second or third of them remains 
in the form of a thin and bent-down lamella; near the anterior ex- 
tremity the same thing is to be seen, but the lamellee are less pro- 
duced. The pallial sinus is tongue-shaped, and its upper line runs 
in a horizontal direction. The valves are tolerably solid, but trans- 
parent, and the teeth of the hinge are very thin, except the lateral 
