62 JOURNAL OF CONCHOLOGY, VOL. 9, NO. 2, APRIL, 189S. 



,S. vitreum Sars has been dredged off the Faeroes by the ' Light- 

 ning,' and S. quinquangulare Forbes in the Faerce Channel by the 

 ' Triton.' 



S. affine Sars. 1 — Sound of Sleat, 75 — 95 f. (Somerville and J.T. M.): 

 Loch Fyne, 56 f. ; Minch off Loch Boisdale, 72 f. Half the speci- 

 mens were living. Dr. Robertson is said to have taken it from 

 '•material dredged off Skate Island, at the mouth of Loch Fyne, in 

 90 to 100 f.'"- 



Distribution: Channel Slopes; Atlantic off Ireland and off Portugal, 

 690 f. to 1,380 f. ('Porcupine') ; Lofoden Isles, 100 — 300 f. (Sars) ; 

 Nova Scotia, 35 f. (Verrill) ; North Atlantic, 1,450 f. ('Valorous'). 



This lives with S. lofotense, and differs from that species in being 

 shorter, broader, less cylindrical, and without the conspicuous rings 

 of growth. It is in no part cylindrical, but gradually increases from 

 apex to base, and the apex, though similar, is blunter or broader. 

 L.j 0*15 ; B , C03 inch. With regard to the proportions of length 

 and breadth, the extreme forms of the two species meet, slender 

 examples of 6". affine approximating to broad specimens of 6". lofotense-. 



GASTROPODA. 



Chitonidae. — There seem to be insuperable difficulties in arrang- 

 ing the Chitonidae on a satisfactory basis. There are, it is true, various 

 "systems" awaiting acceptance, all differing more or less from each 

 other, the difficulty being to reconcile what is apparently irreconcil- 

 able. No group of mollusca has given rise to greater controversy, 

 and, it should be added, to greater research of a laborious and baffling 

 nature by some of the best naturalists. But Mr. W. Ff. Dall, whose 

 opinions on the classification of the Chitonidae are entitled to great 

 weight, writes that " the absence of any well-marked types by which 

 this order might be divided into families, or even sub-families, is very 

 remarkable, and in this respect the variations of the dentition agree 

 with the other characters of shell-plates, girdle, and internal structure. 

 This has already been remarked as regards the girdle and shell by 

 Dr. Carpenter, who recognised that even his chief divisions of the 

 order into Regular and Irregular Chitons failed to possess distinct 

 family value." 3 



Among some further notes in the same interesting work, Mr. 1 >all 

 states that " Chitons in the adult condition are destitute of eyes or 

 tentacles, and exhibit evidences of degradation anteriorly. They 

 differ from most molluscs in that the shell does not appear on the- 



1 Fork. Se/s&. Christiania, 1864, p. 299, pi. vi., f. 34-35. 



2 Trans. N. H. Soc. Glasgcnv, n.s. , vol. 2, p. 152. 



3 Exploration of Alaska, art. 4, p. 74 {Bull. U.S. Nat. Mus., vol. 1). 



