216 PERUSSACIA. 



Type F. gronoviana. Distribution, around the Mediter- 

 ranean in Europe and North Africa; Atlantic Islands. 



Lieut.-Col. H. H. Godwin- Austen describes the soft anatomy 

 of F. gronoviana as follows : 



"The animal (pi. 42, * figs. 76, 77) is of a fine bright sea 

 green colour: the eye-tentacles are dark and thick at their 

 bases, which are contiguous; the oral very short and blunt; 

 muzzle retractile, and can be produced considerably. It is of 

 darker tint at the extremity of the foot, which has a distinct 

 mucous gland with a truncate lobe above it. There is a well 

 marked pedal line parallel to the edge of the foot, from 

 which a series of regular transverse furrows extends to the 

 dorsal side; but the intervals between these furrows are 

 smooth, not papillate : this is seen to extend to the muzzle ; 

 but from the oral tentacles the whole upper part of the neck 

 is strongly and longitudinally grooved. The animal when 

 fully extended is long and narrow, end of foot equal with 

 apex of shell when moving; and the mantle is all round 

 slightly reflected over the thin margin of the peristome. The 

 right dorsal lobe is small, the left is larger. 



"The odontophore (pi. 42, fig. 78) consists of over a hun- 

 dred rows of teeth, about 60 in each row, with a very con- 

 siderable difference in the size of the centrals and laterals, the 

 centre being very small, bluntly tricuspid, on an elongate ob- 

 late base ; the next seven having a long pointed central tooth 

 with the two smaller on either side; the outer laterals are 

 minutely evenly tricuspid on broad, oblong rectangular bases. 

 The dental formula is 22, 7, 1, 7, 22. The jaw (pi. 42, figs. 

 73, 74) is peculiar, not hard and chitinous as is usually the 

 case, but thin and elastic, consisting of a thin membranous 

 ribbon, closely ribbed or rather folded longitudinally, and 

 presenting on the anterior side a zigzag or serrated edge. This 

 elastic plicate structure of the jaw is thus quite in accord and 

 adapted most admirably to the retractile muzzle of the ani- 

 mal. The buccal mass is well developed, of rounded form; 

 the salivary ducts short, the glands of unequal size. 



"Generative organs, (pi. 42, fig. 75). The penis (fig. 75, p) 

 is short, fusiform, conical near the junction of the 



