294 JOURNAL OF CONCHOLOGY, VOL. 9, NO. IO, APRIL, I9OO. 



and widely diffused species is of course extremely variable, and 

 especially with respect to dimensions and number of ribs. Other 

 naturalists must exercise their own judgment as to considering 

 O. terebellum or moulinsiana, and O. suturalis alias emaciata or sylvestri 

 or penchinati, as well as other forms described as species, distinct and 

 not mere varieties. I would not have united them with the typical form 

 if it had not been for the examination and comparison of an immense 

 number of intermediate specimens from different localities." 1 In the 

 type, the variability is that of comparative length to breadth, and 

 degree of sculpture; but in the form designated var. stituralis the 

 variations are most perplexing. They have not much affinity with the 

 true suturalis (=striatus) of Philippi, which is very small, slender, 

 fragile, and cylindrical, with hair-like strise; but the British form of 

 suturalis is a large, broad, and coarse form of var. gracilis Phil, and 

 var. inter mixta Mtros., with a sprinkling of the vars. gracilenta and 

 prceasa, and some narrow forms of the type, the whole series appear- 

 ing to be in a state of fusion and impossible to differentiate; that is to 

 say, certain specimens of nearly all these varieties are to be found on 

 the British coasts, but after the examination and allocation of the 

 above forms, a large residue will be found unascribable to either of 

 them or to each other. This species will give more trouble than any 

 other member of the genus, not in making out the species, which may 

 always be known by its specific sculpture, distinct from any other and 

 never varying except in degree, but in separating the many puzzling 

 varieties and forms, than which nothing can be more confusing or 

 hair-splitting. Collectors meeting with any of these forms on our 

 coasts which cannot be assigned to the present named British varieties, 

 will not be far wrong in classifying them under the next very appro- 

 priate name — 



Var. intermixta Mtros. 2 (nom. sudst.)=0. Jeffrey si B.D. & D. — 

 This is a frequent shell on our coasts, as well as from a raised beach 

 in Skye (T. Scott) ! and differs from the type in being cylindrical, the 

 last whorl equal with the preceding, a smaller mouth, and a keeled 

 base. Compared with var. suturalis it is coarser in sculpture and 

 broader throughout. This is the variety specimens of which will be 

 found to approximate to O. indistincta in outline, but it is a coarser 

 shell generally. It is figured by Searles Wood from the Crag deposits 

 as O. pupa Dubois (a fossil species), with a doubt as to whether it is 

 really the same as Dubois' species; I believe them to be different; 

 while Forbes and Hanley say that Wood's species is O. excavata ; but 

 that is an error; it is without doubt the form of O. interstincta I am 

 now describing. 



1 Moll. "Lightning" and "Porcupine," Proc. Zool. Soc, 1884, p. 353. 



2 Nomenclatura Gen. e Sp. Conch. Med. p. 87. 



