WOODWAED : ON SOME SPECIES OP FISIDIUM. 219 



parison of his figures with the diagram on pi. ii of the " Catalogue ", 

 and vaunts the superiority of his method. This eulogy must surely 

 have been penned ere the reproductions of his drawings had been 

 received from the engraver, for if I was unlucky in having my 

 excellent photographs spoilt as they were by bad coUotyping, he 

 has been still more unfortunate. Yet when the wrecks of his 

 drawings are carefully examined by one acquainted with the two 

 species it looks as if the draughtsman had detected and figured 

 the diiTerences in c. iii of the hinge. 



Mr. Stelfox states that he has seen other examples of P. nitidum 

 similar to the Boveney specimen from other localities. Is it possible 

 that just as in the beginning I came to grief over P. hihernicum 

 he has now missed the opportunity of extending our knowledge 

 of the range of P. steenbuchii 1 



ADDENDUM. 

 Bead lOth June, 1921. 

 Eegrettable though it be, the trivial names of two more species 

 of Pisidium will have to be changed. Both P. pusillum and 

 P. ohtusale were taken by Jenyns at second and third hand from 

 names given to species which prove indeterminate and consequently 

 not available under our modem regulations as to nomenclature. 

 The following new names are consequently proposed : — 



Pisidium pusillulum, nom. nov., vice P. pusillum, Jenyns (of B. B. 

 Woodward), non Gmelin, nee Turton. 

 What the Tellina pusilla of Gmelin (Linn. Syst. JSTat., ed, 13, i, 

 pt. 6, 1791, p. 3231) really was is not now ascertainable. The name 

 was subsequently taken over by Turton in 1819 (Conch. Diet., p. 167) 

 without reference to Gmelin, but in 1822 (Conch. Brit., p. 251, pi. xi, 

 f. 16, 17) when changing the name to Cyclas pusilla he refers to 

 Gmelin. Turton described the shell as " oblique tumid in- 

 equilateral ", and evidently included all the smaller species of 

 Pisidium under the designation. Nine years later, Turton (Manual, 

 1831, p. 16, f. 7) modified this to " obliquely suboval, convex ". 

 Jenyns, when he adopted the name from Turton in 1832 (Trans. 

 Camb. PhU. Soc, iv, p. 302, pi. xx, f . 4-6), on the other hand, speaks 

 of it as " Testa variabilis, plerumque orbiculato-ovalis, interdum 

 suboblonga margine dorsali recto, vix insequilateralis ". Jenyns 

 evidently in the three varieties distinguished by him included more 

 than one form which would to-day rank apart. Of the " two extreme 

 varieties " figured by him, one was probably the personatum of 

 Malm, as suggested by me (Catalogue, p. 7), and subsequently by 

 Mr. Oldham (Journ. Conch, xv, 1918, p. 237), who further found 

 direct evidence on other tablets in the Jenyns collection of the 

 presence of Malm's species under Jenyns' name. Since, however, 

 Jenyns' name is inadmissible, all further discussion as to what con- 

 stituted his species is unnecessary. 



