of the Land and Fresh-water Shells of Suffolk. 151. 
Testa 2 lin. longa, 22 lin. lata, cornei coloris, glabra, striata, vix 
sulcata, anteriùs planiuscula. 
I first received this species from Dr. Leach, and a very di- 
stinct one it is. It belongs to the same group as T. amnica, 
having the hinge on one side; it is smaller than that species, 
but more tumid in proportion; and its decisive characteristic 
arises from a curious eave-like projection at the bases of the 
umbones. 
Sparingly in the stream at Holbrook with T.amnica. "They 
both seem to prefer a gravelly or sandy bottom. | 
Dr. Leach named this shell after his friend Professor Hens- 
low, who, I believe, was its first discoverer. 
.6. Myritus ANATINUs: Trans. Linn. Soc. vol. viii. p. 110. 
This species, in some situations, has its wmbones decorticated ; 
in others the epidermis is entire. This difference cannot be - 
assignable to the roughness or smoothness of the component 
parts of the soil in which they are imbedded ; because, in rivers 
with a gravelly bottom, I have found them with the epidermis 
entire; in ponds, whose bottoms consisted of a soft mud, with 
the umbones decorticated. 
Common in most rivers, and in many ponds. "Those found in 
Mr. Kirby's pond at Darham, in the river at that place, and in 
Campsey Mere, vary from each other. 
7. Mytitus Macura. Trans. Linn. Soc. vol. xiii. p. 86. 
Ponds in my brother's garden at Campsey Ash. 
Described as distinct from M. anatinus in a paper which the 
Society did me the honour to publish in their Transactions ; and 
I am confirmed in that opinion, from the anterior area in both 
adults and young being sloped upwards ; which is the case in the 
young only of M. anatinus. 
12. Turso 
