STEI.FOX : PISiniUM FAUNA OF THE GRAND lUNCTION CANAT.. 30I 



this character hi the type being produced by the abnormal tumidity 

 of tliat form, which unfortunately is a most aberrant one. From 

 P. obtusale it may be separated by its smaller umbones, which are 

 generally more centrally placed, its more regular and rather stronger 

 striation and its much longer c. 2 ; but the chief character, and the 

 simplest, which distinguishes it from that species is its p. Ill, 

 which does not tend to coalesce with /. / towards the umbo. In 

 some cases it tends to approach F. fniliuin in general appearance, 

 but the ventral margin of F. hihernicum is much more curved than 

 in F. miliutn and the ligament pit of the latter is longer and straighter. 

 The animal of F. hibernkum is frequently of a bright rose pink colour.^ 

 [P. steenbuchii (MoUer). Plate 9, figs. 17-20. 



A single shell collected by Mr. J. E. Cooper at Boveney, Bucks., 

 has been referred to Holler's species by Mr. Woodward, and is 

 recorded in his Catalogue, p. no, from this locality, though for some 

 reason the record is omitted from the map of distribution on the 

 same page. By the kindness of Mr, Cooper I have been able to 

 examine this unique specimen, as well as to make drawings of it, which 

 latter will be found figured on plate g. A comparison of my figures 

 with the diagrammatic figures of Mr. Woodward's F. steenbuchii — 

 Catalogue, plate II, fig. 7 — will show that there is not very much 

 similarity between them. The Boveney shell, I would suggest, is a 

 rather uncommon variety of F, tiitidum^ ; somewhat similar specimens 

 occur in the Thames and occasionally turn up in other districts.] 



List of Papers and Works referred to above. 



1. Catalogue of the British species of Pisidium (Recent and Fossil) 

 in the collections of the British Museum (Natural History), with 

 notes on those of Western Europe. By B. B. Woodward, F.L.S., &c. 

 London. 191 3. 



2. Fauna Molluscorum terrestrium et fluviatilium Svecai, Nor- 

 vegise et Danse. By C. A. Westerlund. Stockholm. 1871-73. 



3. Deutsche Excursions MoUusken Fauna. By S. Clessin. 

 Niirnberg. 1885. 



4. On Two Species of Pisidium (Fossil) New to Ireland {F. 

 supinu?n and F. parvulum). By R. A. Phillips, M.R.I. A. Iris/i 

 Natu7-alist, vol. xxv., pp. 101-105, pi. 2, 1916. 



5. 0'^^ the recent misapplication of the names F. pusilban and 

 F. nitidum of Jenyns. By A. W. Stelfox, M.R.I.A. Journal of 

 Co7ic]iology\ p. 235 ante. 1918. 



1 For a fuller description of P. hibernicton and figures see R. A. Phillips and A. W. Stelfox 

 on ''Recent extensions of the range of /". hibef-nicuiii," Irish Naturalist, vol. xxvii., pp. 33 — 

 50, plates I and 2, 1918. 



2 See note below. 



