302 JOURNAL OF CONCHOLOGY, VOL. I5, NO. lO, SEPTEMBER, I918. 



[Note added in the press]. Since the present paper was read, a reply 

 to my contention (5) that Mr. Woodward's P. pusilhnn and his P. 

 persoiiatiim are respectively tlie P. nitidtim and P. pusillum of Jenyns 

 has been published in this Journal (p. 260 ante). In this Mr. Wood- 

 ward confines himself mainly to a denial of my contention and to 

 matter the revelancy of which I have so far failed to appreciate, but 

 he adduces evidence which in my opinion supports my view. Thus 

 he says " P. piisilluvi, as I understand it, is common in Ireland, and 

 especially fine in the shell-marl deposits." Our Irish shell-marls are 

 essentially "open water" deposits, being mainly composed of the 

 decayed stems of species of Chara. If we turn now to the works of 

 the older British authors, including Jenyns, it will be seen that their 

 P. pusillwn is always spoken of as inhabiting precisely the opposite 

 kind of habitat, or that in which Mr. Woodward's P. personatum most 

 frequently occurs. It is significant also that the specimens in the 

 Hanley Collection in the British Museum labelled '^'^ P. pusilhnn, 

 British," which Mr. Woodward thinks were probably used by Forbes 

 and Hanley for their illustration of that species, are Mr. Woodward's 

 P. perso7iatu7n (Cat. p. 63). The specimen (not two specimens as 

 stated by Mr. Woodward) of Jenyns' P. pusillum at Bath, referred to 

 in Mr. Oldham's notes (p. 237 ante~)., is that figured by Jenyns in his 

 Monograph, plate xx, fig. 4. When Mr. Woodward claims to be the 

 first reviser of Jenyns' P. pusillum and states that "the idea of a type 

 in its modern conception had not been evolved in Jenyns' time," he 

 must have forgotten that when referring to Gray's similar proposed 

 revision of Jenyns' composite P. pulcheUum (Cat. p. 8) he has said : 

 " This forcible exchange of type is not recognized now-a-days." 



As regards the shell figured by me as P. nitidum (p. 237 ante), Mr. 

 Woodward says that it is a good representation of his nitiduvi and 

 quite unlike his pnsilhim, but I am still of the opinion, after once 

 more making careful comparisons between this and his figures, that it 

 agrees in all essential characters with the description and figures of 

 \\\% pusillum ; and that the shell from which the diagrammatic figure 

 of his pusillutn was made (Cat. pi. i, fig. 8) is conspecific with that in 

 the Hyndman Collection in Belfast labelled P. nitidum. It would 

 assist students of this §roup if Mr. Woodward would disclose the place, 

 and nature of the habitats, from which the shells he has diagrammati- 

 cally figured in his Catalogue were obtained, so that further specimens 

 might be collected and these studied alive. It is my belief that only 

 by close study of the ecology of the Pisidia in the field will their 

 secrets be discovered. In this statement I have the support of 

 Jenyns, who in his later paper (1858) says: — "Having, however, 

 occasionally had shells sent to me which were erroneously supposed 

 to belong to the species in question, I must again caution collectors 



