FAECAL PELLETS FROM MARINE DEPOSITS 



23 



this ovoid shape of pellet is common to very many kinds of animals, it is probable 

 that the ones found in the deposits represent the faeces of several different species. 



Smooth rod-shaped pellets with a diameter of up to 0-15 mm. were found abundantly 

 at St. WS 144, and in smaller numbers at St. WS 502. A single specimen of a simply 

 sculptured rod was found at St. 375. It consisted of a rod, circular in section, with a 

 single groove along one side (Fig. i a). In transverse section it appears to be composed 

 largely of diatom remains, more so in fact than the mud from which it came, or the ovoid 

 pellets found there, so that it must be the pellet of a selective feeder. I would suggest 

 further that it is probably the pellet of a mollusc, although none are at present known of 

 quite this type. 



Fig. I. Transverse sections of pellets from marine deposits. 



a, Pellet of a mollusc ?, from St. 375. b, Pellet of Niiciila sp., 

 from St. WS 144. c, Pellet of Niicida tenuis, from the Clyde. 

 d, Pellet of Niicula moorei, from the Clyde. 



A second and more complexly sculptured type of rod-shaped pellet was found 

 abundantly at St. WS 144, and consisted of a rod up to o-i6 mm. in diameter with a 

 series of longitudinal grooves on the surface. In transverse section (Fig. i b) this also 

 appeared to be formed almost entirely from diatom remains, and may also therefore be 

 classed as a probable selective feeder. So few pellets have as yet been described that it 

 would be unreasonable to attempt to identify an unknown pellet with any given animal 

 without a considerable knowledge of the fauna of the locality. But this pellet in all 

 respects resembles those at present known for the genus Nucula, and it is at least 

 reasonable to advance the possibility of its belonging to this genus. Nucida pellets are 

 all rods with longitudinal grooves ; and all the species which I have so far examined may 



