196 JOURNAL OF CONCHOLOGY, VOT,. I4, NO. 7, JULY, I9I4. 



It was first described by Pfeiffer in 1850/ this author adopting 

 Charpentier's manuscript name of gigaxii, and it is of some interest 

 to find in the original description that British specimens are referred 

 to, viz.: — "Commons near Highbycombe, Bucks.," Cuming. 



In 1853- the same author gives a further description of the species 

 and includes a larger variety, "(i major: diam. maj. i2|, min. io|, 

 alt. 7 mill." In this work he gives the distribution as France (Aries, 

 Vaucluse, Grasse, Valence), and Britain (including the var. /3). 



Both the small form (diam. 8 mill, from Vaucluse, etc.), and the 

 larger form, var. f/iajor Pfr. (diam. maj. \2\ mill., from England), are 

 excellently figured by Pfeiffer,-' and he refers to these figures in his 

 later diagnosis of 1853. Tryon^ also adopted Pfeififer's figures 23—25 

 as typical of the species. 



Through the kindness of the Rev. Canon Horsley I have been able 

 to see and compare a shell of H. gigaxii from Avignon, Vaucluse, 

 and find it agrees in every way with the figures and descriptions 

 referred to above. The same remark applies with equal force to some 

 specimens labelled H. heripensis Mabille from Lyons, kindly lent to 

 me by Mr. B. R. Lucas. 



With this experience I have now no hesitation in considering the 

 large form (var. major Pfr.) as undoubtedly representing the shell 

 described by Mabille'^ as H. heripensis, under which name it has been 

 brought forward as a British species by Mr. A. W. Stelfox'' to whose 

 interesting paper I would refer collectors for comparative figures and 

 descriptions. 



The most obvious characters distinguishing it from H. caperata are 

 undoubtedly the beautiful fine striation and the eccentric umbilicus. 

 The shells, too, are relatively flatter than in H. caperata. There is 

 quite an appreciable difference in the character of the umbilicus 

 among the shells of one gathering from any one locality. In some 

 specimens the whole of the interior of the columella and a large por- 

 tion of the penultimate whorl are visible ; in others, whilst the 

 penultimate whorl is amply exposed, the interior of the spire is 

 scarcely visible owing to the pinching in, as it were, of the shell. 

 This character does not appear to be connected with any particular 

 form of shell, whether flat or with somewhat produced spire, as I 

 have met with it in each kind in specimens from several localities. 



Internally the two species also differ somewhat in pigmentation, 

 a point which has recently been fully dealt with by Prof. Boycott 



1 Zeit.f. Mai. p. 85. 



2 Monog. He lie. Viz>., iii., pp. 133-4. 



3 Conch. Cab., i., 12, p. 316, pi. 128, -f. 23 — 30. 

 Manual, iv., pi. 3, f. 25 — 27. 



5 Bull. Soc. Zool. France, 1877, p. 304. 



6 Proc. Malac. Soc, Lond. ,x., 1912, p. 39, pi. ii. 



