494 



operculum with a still narrower aperture. The branchiae are 

 semilunar, one large, one smaller, of a dark brown colour; 

 immediately above the larger one are the coarse pale yellow 

 mucous filaments, which are edged with a dark border. The 

 organe generateur male is a very long, narrow, strap-shaped 

 appendage, pointed at the end, springing under the right ten- 

 taculum, and lying doubled up and reflected back in the 

 branchial cavity. The ovarium and liver occupy all the 

 posterior volutions, and run mixed together to near the 

 pylorus ; the two organs are easily distinguished, the ovarium 

 being pale yellow, and the liver red-brown. In the male the 

 testis replaces the ovarium. I have a little exceeded the limits 

 of ordinary description on account of this animal being the 

 type of the section. 



This elegant species is sufficiently abundant in the coralline 

 zone at Exmouth. 



M. GINANNIANUS, nobis. 



Pleurotoma Ginannianum, Philippi, Moll. Sicil. 



Mangelia nebula, Brit. Moll. iii. p. 476, pi. 114. f. 7, 8, 9; (animal) 



pi. R.R. f. 7. 



Animal spiral ; ground-colour white or pale yellow. Mantle 

 plain, even, except the branchial fold, which, when the animal 

 is in motion, floats freely beyond the canal, and from its con- 

 stant movement appears to act as a feeler; the mantle also at the 

 upper part of the outer lip lines a very inconspicuous emargi- 

 nation of the shell, forming a minute anal conduit. The head 

 is small, white, compressed, and does not at all interfere with 

 the basal conjunction of the tentacula ; the proboscidal fissure, 

 as in Murex undatus, is below the coalescing membrane ; the 

 tentacula are short, flake-white, with eyes at the terminal 

 surface of external offsets nearly extending to their points. 

 The foot, when fully extended, reaches to the third or fourth 

 posterior volution; it is pale yellow below, with marginal 

 transverse white markings, and sprinkled on the upper surface 

 with intense flake-white spots ; it is subrotund in front, scarcely 

 auricled, narrow, gradually tapering to a blunt, slightly emar- 

 ginate point. There is no operculum, and in this respect and 

 in all the other organs it agrees with Murcx gracilis. This 



