Mr. W. H. Benson on the Animal of Diplommatina. 433 



intermediate spaces being glabrous. It was this fact which led 

 me erroneously to suppose that the common British plant ought 

 to be considered as the T. Chamcedrys of Fries, and caused me to 

 so name it in the 3rd edition of my ' Manual.' In the ' Fl. Sile- 

 sise ' (p. 167) attention is justly directed to the fact that in T. Ser- 

 pyllum the elongated forms have the more slender shoots, whilst 

 in T. Chamcedrys the more extended the shoots the thicker they 

 become. 



I possess T. Chamcedrys from the DeviFs Ditch in Cambridge- 

 shire; Box Hill, Surrey {T. sylvestris) ; and How Capel, Here- 

 fordshire. It flowers throughout the summer, and, I think, likes 

 rather a damper and more shaded situation than its ally. 



In all pi-obability these two species wiU be found throughout 

 the kingdom, but it is to be desired that botanists should care- 

 fully note their presence in all parts of the country in order that 

 their true distribution may be ascertained. 



XL. — Further Observations on the Animal of Diplommatina 

 {including a Note by Capt. T. Hutton). By W. H. Benson, 

 Esq. 



Dr. J. E. Gray, and after his example Dr. L. Pfeififer, being at 

 issue with Capt. Hutton and myself on the subject of referring 

 the genus Diplommatina to the operculated or inoperculated pul- 

 moniferous Testacea, the holders of the latter opinion being 

 moreover those who have studied the animal in a living state on 

 its native mountains, and who ground their persuasion on the 

 view of many hundred specimens, while the maintainers of the 

 contrary part can only refer to two or three Museum* specimens 

 which must have passed through several hands before submission 

 to scientific examination, anything which can tend to throw light 

 on the question will be acceptable to conchologists. 



The occurrence of a single operculum in a living specimen, or 

 in one conveyed from the Himalaya to England, secured from all 

 risk of being tampered with, either ignorantly or designedly, would 

 be sufficient to settle the matter in the affirmative, even although 

 thousands should be found destitute of this accessory piece; 

 but I cannot allow that such a certainty has yet been arrived at 

 as to induce us to reject the accumulated evidence of opposing 

 observations. No apology will be necessary for the publication 



* Dr. Pfeiffer's note, ' Monogiaph/ p. 121, " CI. Benson operculum non 

 observavit, tamen in copiosis Mussel Britannici speciminibus adest, et ideo 

 genus familise Cai'ychiadarura adnumerat," leads to an en-oneous conclu- 

 sion. Dr. Gray has assured me that there aie only two or three opercula 

 in the British Museum. 



