146 ANATINID^E. 



The ground colour of the animal is hyaline white ; the mantle 

 is considerably extended beyond the margins of the shell, and 

 is of azure hyaline, edged with brilliant silvery, close-set, sym- 

 metrical, blunt, short, but distinct dentations, which extend 

 on both sides to near the beaks ; consequently it is open from 

 the anterior side, throughout the ventral range, to the sessile 

 anal tube, which is scarcely visible, being within the margins 

 of the shell, from which we saw ejected the elongated oval 

 drab pellets : this is the only apparent siphonal orifice. The 

 foot is very large, long, broad, subtriangular, hyaline, well 

 suffused with flake- white points ; it is usually protruded in the 

 centre of the ventral range, and the animal frequently passes 

 it from stem to stern ; it is slightly geniculated and has a 

 decided byssal groove. 



The animal is lively, marches with rapidity, and in its course 

 turns from side to side, sometimes resting the shell on the 

 ventral range in an upright posture. The branchiae and palpi, 

 from their minuteness, escaped observation. It inhabits the 

 coralline district at Exmouth, from which we have obtained 

 many live examples. 



A. FERRUGINOSA, nobis. 



Montacuta ferruginosa, Brit. Moll. ii. p. 72, pi. 18. f. 5, 5 a & 5 b. 

 Myaferruginosa, Montagu et Auctorum. 



This species has not occurred to us alive, and up to 1849 

 all the information obtained from naturalists was, that the foot 

 is large, the posterior tubes absent, that it has only a sessile 

 orifice, and that the anterior end of the shell is the longer 

 side. But since that date, in 1850, we have had the advan- 

 tage of seeing Mr. Alder's paper on the Montacuta ferruginosa 

 in the ' Annals of Natural History/ N. S. v. p. 210, pi. 6. f. B. 

 We collect from the account, that the mantle of the animal 

 is considerably produced anteally, and fringed for a large por- 

 tion of its extent. A comparison of these points with our own 

 notes on the Anatina bidentata, which authors style Montacuta 

 bidentata, of which we have examined many live examples, 

 shows the concordance of the two species ; in both, the anteally 

 produced and fringed mantle, the character of the foot, and 



