432 FATELLID.E. 



inch in length, and from thence to P. Irrvis, of three- 

 quarters of an inch long - , and finds the organs similar in all 

 respects, with a slight variation of colour dependent on 

 age. 



The mantle is often bordered by a grey line, and is 

 fringed with numerous (" fifty to sixty-five," according to 

 Mr. Clark) fine cirrhi which vary in length in different 

 individuals. The branchiae form a fringe of minute white 

 plates between the foot and mantle, interrupted in front of 

 the head, and terminated on each side nearly symmetri- 

 cally. In a specimen three-fourths of an inch long we 

 counted about a hundred branchial plates ; the hinder ones 

 were longest. The head is rather large, terminating in- 

 feriorly in a short proboscis, which has puckered edges, 

 but is not emarginated below ; the tentacula are rather 

 short, obtuse, and linear ; they bear minute eyes on the 

 outer sides of their slightly swollen bases. " The foot is 

 oval, very thick and dense, and the viscera are pale 

 coloured ; the stomach from the pylorus gives forth a very 

 long intestine, greatly convoluted between the lobes of the 

 liver, which is light green (sometimes pale yellow, E. F.), 

 and near the posterior end doubles and terminates as a 

 rectum, accompanied by the oviduct a little to the right of 

 the centre of the neck, under the right tentacle, not at the 

 side of the body; the vent is double the size of the oviduct, 

 which progresses from the oval, pale red brown minutely 

 granular mass of the ovarium, placed immediately above 

 the foot, at the posterior end " (Clark MSS.). The 

 lingual ribband is not so long as in P. vulgata ; it is less 

 than the length of the body ; in a specimen nine-twelfths 

 of an inch long, it measured seven-twelfths, and we counted 

 eighty transverse series of teeth. Its axis is formed of four 

 nearly equal teeth, with parallel sides, and hooked brown 



