WlTEl A LIST OF SPECIES OBSERVED. 225 



to ail authority, who had pronounced them to be undoubtedly H. 

 simi/is. 



This appeared to me to be conclusive evidence that the shells 

 were certainly the Hydrobia similis of Draparnaud, and from that 

 date until October 4th, 1889, I had no further doubt al)0ut them, 

 and during that period I sent out many exchanges of this species to 

 various correspondents. 



To Mr. J. T. Marshall, of Torquay, belongs the credit of being 

 the first to positively say that it was not H. similis, although also for 

 a time he considered these shells to be Jeffreys' variety ovata of H. 

 veyitrosa.^ These opinions of good conchologists must be my excuse 

 for being so easily misled in respect of this shell. Certainly, if I had 

 thought that there was the least doubt as to its identity, I should have 

 taken care to submit specimens for observation and comparison to 

 some practical conchologist well acquainted with the family. I also 

 regret that many correspondents have at various periods received as 

 an exchange these Hydrobice as authentic H. similis. I feel confident 

 that these mistakes originated owing to the great difficulty of obtain- 

 ing shells of^. similis, and also Jeffreys' variety ^z'rz/d' of -^ vetitrosa, 

 and I am certain that at that time the real Simon Pure was to be 

 found in the shell cabinets of very few collectors.* 



As the dispute waxed warm between the advocates oi H. jenkinsi 

 versus H. ventrosa, var. ovata, I felt the necessity of procuring living 

 examples of all the species under discussion, and made frequent 

 excursions to the marshes in all sorts of weather. Having supplied 

 Mr. Smith, of the British Museum, with living examples of the three 

 species, I kept a number in Aquaria under my own observation for 

 many months. During this time I had every opportunity of noting 

 their difference in habit and capability of adapting themselves to 

 water which was more fresh or more brackish than that to which 

 they had hitherto been accustomed. 



Close examination soon convinced me that Mr. Smith was right 



3 This statement may be correct so far as the particular specimens sent to Mr. Marshall by his 

 correspondents as //. siiittlis (" Journ. of Conchology," vol. vi., p. 140) were concerned; but it 

 seems to be clear that the credit of positively determining the Essex and Kent specimens as con- 

 stituting a new species belongs to Mr. E. A. Smith and Mr. Walter Crouch, who came to that 

 conclusion as long ago as February 2nd, 1889. (Essex Nat., iv., pp. 212-214.) — Ed. 



4 The first H. jenkinsi dcpo?<i\.e:d in the collections at the British Museum were, we believe, the 

 three spec'mens sent on 29lh January, 1889 (with other species o^ Hydrobia) by Mr. W. Allen, of 

 Canning Town, to Mr. W.ilter Crouch, who, noticing the carinated whorls, concluded at once 

 that they were new. They were taken on P'ebruarj' 2nd by Mr. Crouch to the Museum, and Prof. 

 Flowers' acknowledgment, dated March nth, runs thus: "Three specimens of a species of 

 Hydrobia, new to the British fauna, from Beckton, near North Woolwich " (vide E. A. Smith, 

 "Journ. of Conchology," vol. vi., p. 142 ; Essex Nat., vol. iv., pp. 128 and 212 ; and " Science 

 Gossip," 1891, p. 163). Subsequently Mr. Jenkins sent a series from the Erith Marshes, and Mr. 

 Crouch a set of thirty-six examples from Beckton. — Ed. 



