68 littorinidtE. 



distinct and bluntly scalarifovm, owing to a brief horizontal 

 compression at their upper suture ; otherwise they are 

 moderately convex. The body, which is not particularly 

 rounded, occupies dorsally from one half to three-fifths of 

 the length of the shell ; the commencement of the basal 

 declination, which is abrupt and subretuse, is somewhat 

 angular. The breadth of the penult whorl is nearly twice 

 its length. The aperture is of an uniform chalky white, 

 is suborbicular or rounded ovate, longer than broad, and oc- 

 cupies from two-fifths to nearly one half the length of the 

 shell ; it is sometimes a little prominent, and often sub- 

 angular, and a little effuse at the anterior extremity. The 

 outer lip is simple and acute. The pillar-lip is broad and 

 flattened, increases in width anteriorly, and shelves consi- 

 derably inwards ; it is neither particularly oblique, nor 

 canaliculated, but at most is indented with an obscure and 

 narrow groove-like chink ; the free edge is concave. The 

 axis is imperforate. The average length is only five lines, 

 and the breadth three ; but these dimensions are often 

 exceeded. 



Unfortunately we do not possess any note of the animal 

 of this, perhaps the scarcest of our Lacunee, though common 

 enough in many localities, especially in the North. It has 

 the widest vertical range of any of our species, extending 

 from low- water-mark to as deep as fifty fathoms (Thomas). 

 Like the last species it is a favourite food of the haddock 

 (Knapp). Mr. A. Hancock has found it alive at Culler- 

 coats in pools at low water. 



Note. — We have not seen the L. retusa of Bro^vn (111. Conch. G. B, p. 128, 

 pi. 10, f. 52, 53), the delineation of which somewhat reminds one of the fry of 

 Paludina, but copy his description verbatim ; 



" Very thin, subglobose, hyaline, and of a greenish-brown colour ; spire 

 extremely small, hardly elevated above the body, and consisting of two volutions; 



