498 MUBICID^E. 



The shells exhibit two well-marked varieties ; the one the 

 typical M. linearis, with more regular subdued spiral striae; 

 the other is more scabrous. The smoother variety is sparingly 

 found in the coralline zone ; the scabrous shells are abundant 

 in the same zone, at Exmouth. I have only examined the 

 animal of the latter ; it is possible the former may be distinct. 

 Exmouth, 3rd August 1850. Since writing the above I have 

 met with a fine live specimen of the smoother variety, and I 

 am unable to detect a variation in them. 



M. ATTENUATUS, Montagu. 



Mangelia attenuata, Brit. Moll. iii. p. 488, pi. 113. f. 8, 9; (animal) 

 pi. R.R. f. 5. 



This beautiful species is in most respects so similar to the 

 Murex gracilis, the type of this section, that to describe it 

 would be nearly a literal repetition of the account of that 

 animal, except that the emargination of the outer lip, which 

 scarcely merits that term, is rather a minute hollow shoot 

 than a scission : there is no operculum. This is a rare ani- 

 mal, but I have examined several from the coralline zone at 

 Exmouth. 



Another variation from the M. gracilis is, that the foot, 

 when fully extended, is as long as the shell; it is bordered 

 with flake-white spots, but no pink marks are mixed up with 

 it either below or above, as in M. gracilis. In this species 

 the only pink or red spots are on the termination of the 

 branchial fold. The organe generateur is of a pea-green 

 colour, and in other respects is precisely similar to that of 

 the type. 



No head- veil or inflation interferes with the coalition of 

 the tentacula. 



M. COSTATUS, Montagu. 



Mangelia costata, Brit. Moll. iii. p. 485, pi. 114 A. f. 3, 4, 5 ; (animal) 

 pl.R.R. f.4. 



Animal spiral, of seven or eight turns, of a pale hyaline 

 ethereal blue nearly throughout, shaded with the most delicate 

 white. The mantle is of the general ground colour, and even 

 with the shell, except the slight depuratory fold which lies in 



