APPENDIX. 521 



minute points of flaky matter of similar hue. The tentacula 

 are flat and strong, and rather clavate at the tips ; the eyes 

 are always carried considerably within the margin of the shell. 

 The foot is narrow, and when fully extended, as long as the 

 shell, with a rather pointed termination. The caudal cirrhus 

 of the opercular lobe is very long and distinct, flattish at its 

 insertion, and tapering to a fine point. This animal is nearly 

 a true Rissoidean. Axis -^V, diameter -^ uncise, in ordinary 

 specimens. 



ASSIMINIA. (P. 380.) 



Assiminia is not placed in the same order as in the Classi- 

 fication, it being removed, provisionally, between Rissoa and 

 Truncatella, as we think, when the animal is better known, it 

 will belong to the latter genus. 



We have in vain called on naturalists to furnish us with 

 some of these animals ; they abound in the tidal ditches of 

 the Greenwich and other eastern marshes ; if they were sent 

 by post on the day of capture, in an ounce bottle filled with 

 the water or moist mud they inhabit, enclosed in a tin 

 cylinder or small wooden box, they would arrive sufficiently 

 lively for examination. 



CHEMNITZIA PALLIDA. (P. 415.) 



The rostrum, or head, is short, broad, rounded or sub- 

 circular at the end, slightly grooved to its base, and speckled 

 with yellow points. The tentacula are not short, but long, 

 subtriangular, not pointed, and have very distinct, small, 

 flake-white terminal inflations; they are bevelled, rather 

 setose, narrow, not much folded or auriform. The animab 

 and those of all its numerous varieties, viz. C. dubia, C. alba, 

 C. nitida, C. albetta, C. rissoides, C. eulimoides, and C. yla- 

 brata, are more or less variously suffused with very minute 

 yellow points, as well as speckled with irregularly deposited 

 dots or larger points of sulphur-yellow, of various intensity of 

 hue; this characteristic colouring will always detect the 

 C. pallida or any of its varieties, as no other Chemnitzia 

 that can be confounded with it is thus painted. 



