of the Land and Fresh-water Shells of Suffolk. 151 



Testa 2 lin. longa, 2^ lin. lata, cornei coloris, glabra, striata, vix 

 sulcata, anteri\is 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. Mytilus anatinus. Trans. Linn. Soc. vol. v'm. p. 110. 



This species, in some situations, has its umbones 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 Barham, in the river at that place, and in 

 Campsey Mere, vary from each other. 



7. Mytilus Macula. 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 ihe^anterior area in both 



adults and young being sloped upwards ; which is the case in the 



young only of M. anatinus. 



12. Turbo 



