APPENDIX. 263 



Vol. iii. p. 84. Rissoa Beanii. 



Mr. Clark notes upon the animal of this species (described by 

 him as R. reticulata, Montagu, and as including R. sculpta), that 

 the " rostrum near its termination at the upper surface, appears 

 to have attached to it two very small similar shields, one on each 

 side, independent of the terminal, minute, subcircular, flat lobes. 

 The eyes are at the external angles of the rather long, slender 

 tentacles, and are placed on short light-yellow or orange pedicles. 

 The foot is subrotund, scarcely auricled. The terminal part of 

 the operculigerous lobe is furnished with three blunt, cylindrical, 

 short cirrhi." 



The animal of Rissoa punciura closely resembles the preceding ; 

 the operculigerous lobe is a very pale muddy reddish brown, 

 marked on each side close to the junction of the foot with the 

 body, with an irregular, rather large, dark smoke-coloured stripe. 

 There is also under the neck, near the eyes, a small red dot. 



Vol. iii. p. 92. Rissoa costata. 



Mr. Clark notes that the animal is hyaline white, except the 

 large black eyes and pale red buccal disk. The tentacula are 

 long and flat. The foot is not auricled in front, and is rounded 

 behind. There is a single distinct caudal cirrhus. 



Vol. iii. p. 117. Rissoa semistriata. 



Mr. Clark has observed the animal of this species, and de- 

 scribes it along with the preceding in the " Annals of Natural 

 History," for October, 1852. It is white, with a pale tinge of 

 yellow. The mantle is even with the shell, except a short minute 

 filament, that is protruded from the portion which lines the 

 upper angle of the aperture. The head is short, with rather long 

 divergent, flattish tentacula, having slightly clavate tips and 

 eyes on gently raised prominences at their external bases. On 

 the tail there are three cirrhi, of which the middle one is 

 longest. 



