194 PLIOCENE MOLLUSCA. 



tlie convexity of the whorls, but they maintain the same general character, being 

 especially characterised by their long, semi-tnbular and sometimes twisted canal, 

 which in the form regarded by Morch and Ponlsen as the typical variety of 

 this species, turns to the left. I have figured one of Dr. Ravn's fossils, together 

 with another from Oakley, with which it closely corresponds. 



S. Okvw belongs to the tortnosus group, but differs sufficiently from that species, 

 I think, to justify its specific separation ; moreover, the latter has not been 

 recorded hitherto from the Iceland Crag. 



Var. Morchii, nov. Plate XXIII, figs. 7—9. 



1877. Sipho sp., Mijrcli and Poulseu, MS. list and plates in Geol. Mus., Copenhagen, no. 12, pi. iv, 

 fig. 1 (unpublished). 



Varietal Characters. — Shell thin, fusiform, whorls 6 or 7, more convex than in 

 the type, regularly diminishing in size, the last ventricoso, excavated below ; 

 ornamented by clearly marked spiral lines, usually very fine ; suture well marked 

 but not deep ; apex planorboid in the Crag specimens, blunt and twisted in those 

 from Iceland ; mouth oval, angulate above ; columella sloping above, nearly straight 

 in the middle, turning to the left where it joins the canal ; canal fairly long, semi- 

 tubular, nearly straight, usually twisted; outer lip thin, regularly curved; inner 

 lip forming a thin glaze on the pillar. 



Dimensions. — L. 35 mm. B. 15 mm. 



Distribution . — Not known living. 



Fossil : Waltonian Crag : Little Oakley. Newbournian : New- 

 bourn. Butleyan : Butley ; probably elsewhere in the Red Crag. Pliocene : 

 Iceland. 



Remarks. — When examining the collection of Icelandic fossils at Copenhagen 

 in 1911, with Dr. Ravn, I was fortunate enough to notice some agreeing with a 

 number of Oakley fossils which had perplexed me for a long time. Although the 

 Copenhagen specimens were labelled ;S^. Olavii, they differed widely, especially in 

 the greater convexity of the whorls and in the canal, from the form which had 

 been figured by Morch and Poulsen as the type of that species (PI. XXIII, fig. 6), 

 agreeing rather with my fig. 8, which in the unpublished Copenhagen list (no. 12, 

 pi. iv, fig. 1) is described as Sipho sj). Dealing only with the Crag shells, I should 

 not have hesitated to regard them as specifically distinct, but Dr. Ravn informs me 

 that in the Morch collection there are some of an intermediate character which in 

 his opinion and in that of Dr. Nordmann connect the two. The view that certain 

 fossils may appear to be specifically distinct in one area while they are specifically 

 connected in another is interesting. I accept their opinion as to the Iceland shells, 



