MARSHALL: ADDITIONS TO "BRITISH CONCIIOLOGY." 209 



Having subsequently had an opportunity of examining Mr. Ma'r- 

 quand's Alderney and other Channel Islands' alleged specimens of 

 D. entalis, as well as other shells under that name in the Guernsey 

 Museum, I have found them without exception to be as I suspected 

 D. vulgare. Mr. Tomlin's examples I take to be in the same cate- 

 gory. Though there would be nothing remarkable in the occurrence 

 of this very common shell in the Channel Islands, yet as a matter of 

 fact I do not know of any reliable record of its presence in those 

 islands. There are certainly no examples in the Jersey or Guernsey 

 Museums, and Mr. Duprey in his list of Jersey shells does not even 

 mention the name. 



var. striolatum Stimps. — -Shetlands ySf. and Saf (Jeffreys) ; 

 N. of the Hebrides iSgf. and 65of. ('Lightning'); Faroe Channel 

 57of ('Triton'); Skye and Hebrides, apparently semi-fossil (Jeffreys). 

 An examination of Norwegian specimens will show the continuity of 

 these two forms as one species. In some parts of Norway they live 

 together and range from the smooth entalis to the sculptured sfrio- 

 latum. D. agile M. Sars and var. orthnim Wats, are in the same 

 relation to each other, and although Dr. Boog Watson considers these 

 two forms to be also varieties of D. entalis, I think they are sufficiently 

 marked off from that species to stand by themselves. 



D. agile M. Sars has been dredged between the Shetlands and 

 Norway in ipyf. (Simpson) ! in the Shetland-Faroe Channel 57of. 

 and 64of. ('Triton'), and in the Atlantic off Ireland in i,ooof. (Smith) 

 and in 34Sf. (R.I. A. cruise). One of the 'Triton' specimens was 

 described by Mr. Jordan as D. (enigtnaticiim n.sp.^ I have seen this 

 shell, which, with his figure and description, is indistinguishable from 

 D. agile. He says that he relies on its "persistent ribs and more 

 slender form" to distinguish it from D. agile, but as a matter of fact 

 these two characters are never constant in any two examples of the 

 species. 



Chiton L. — Montagu described a seven-valved specimen of C. 

 IcRvis as C. septe/nvalvis ; a six-valved Chiton was recorded in the 

 Nautilus for 1901, while a remarkable example of C. contractus 

 Reeve, in the Natural History Museum, has only three valves. 



C. fascicularis L. — The tubercles on the plates are variable in 

 size ; even in specimens found together they are twice as large in 

 some examples as in others, and only half as numerous. In the Sal- 

 combe estuary C. fascicularis lives near high-water mark, on the sides 

 of caves in the rocks, in company with Patella vulgata and OttJia 

 otis, where they may be found breast high crawling freely among the 

 barnacles. 



I Proc. Mai. Soc, 189s, vol. i, part 6. 



