SPIRIALIS. 115 



description, and was suggested by Dr. Fleming under 

 a misapprehension that the type was " a reversed species 

 of Fusus" and allied to " Murex contrarius of Sowerby's 

 'Mineral Conchology.'" Five years after the publica- 

 tion of Heterofusus in^the ' Memoirs of the Wernerian 

 Society/ the author retained the only species of which 

 he seems to have been aware in Fusus. Forbes called 

 the genus Peracle, and Philippi Sccsa. 



SPIRIALIS RETRO VER'SUS*, Fleming. 



Fusus retroversus, Flem. in Mem. Wern. Nat. Hist. Soc. iv. p. 498, t. xv. 

 f. 2. 8. Flemingii, F. & H. ii. p. 384, pi. Ivii. f. 4, 5, and (animal) 

 pi. MM. f. 1. 



BODY more or less tinged with purple : foot-lobes or wings 

 " shaped something like the petals of a catch-fly, rather trun- 

 cated at the extremity, furnished with a small lobe halfway 

 down their undersides, and another small rounded lobe at 

 their lower bases " (Forbes), extremely long (Rang and Sou- 

 leyet). 



SHELL resembling that of Physa in shape, but more rounded 

 at the base, very thin and fragile, almost transparent, glossy, 

 and having a prismatic lustre : sculpture none : colour clear- 

 white, with a faint tinge of yellow in living specimens : spire 

 variable in length, but usually short, regularly elevated ; apex 

 mammillar : whorls 5, swollen, each slightly turreted at the 

 top ; the last exceeds in size half the shell : suture narrow, 

 excavated : mouth trapezoidal, contracted in front, somewhat 

 expanded below, and forming a sharp angle at the basal point ; 

 its comparative length is in proportion to that of the spire : 

 outer lip gently curved, abruptly inflected towards the peri- 

 phery : inner lip wanting on the periphery, and reflected on 

 the pillar, which is straight: umbilicus small, but distinct 

 and deep in full-grown specimens. L. 0-075. B. 0-0625. 



Var. 1. Macandrece. Spire longer. S. MacAndrei, F. & H. 

 ii. p. 385, pi. Ivii. f. 6, 7. 



Var. 2. Jeffreysi. Spire shorter. S. Jejfreysii, F. & H. 

 ii. p. 386, pi. Ivii. f. 8. 



* Turned backwards. 



