LITTOEINA. 341 



nucleus. The buccal apparatus is a deep-red fleshy mass, 

 supported by two thin coriaceous plates, between which, in 

 ordinary-sized animals, a long (at least 2 inches) riband-like 

 white spiny tong-ue issues, passing down the oesophagus, and 

 becoming closely coiled in the stomach; its termination is 

 tinged with red. Immediately behind the buccal mass is the 

 cesophageal cordon, which consists of only two white, subro- 

 tund, flattish ganglions, one on each side ; and behind them 

 are the salivary glands, each formed of a mass of foliaceous 

 granules. There is only one branchial plume, of light yellow, 

 attached to the left side of the mantle and neck of the animal. 

 The verge is a large flat organ, grooved longitudinally, ridged 

 transversely, dentated on one side with two points, one below 

 the other, the lower one with a minute orifice : the female is 

 oviparous. The antepenultimate whorls are always flat in 

 this species, being a condition resulting from the shape and 

 size of the ovarium, which is only adapted for ova; it is, 

 however, much more prolific than the Littorina rudis and 

 varieties. 



This is the common edible periwinkle of the London 

 markets, and the only one, as the females of the L. rudis and 

 all its varieties are viviparous, and cannot be used for food in 

 consequence of the grittiness arising from craunching the testa- 

 ceous pulli ; it is found in all situations, often exposed to the 

 full influences of an open sea, but more usually in estuaries 

 and muddy inlets, which are also the habitats of certain 

 varieties of the L. rudis; it grows to \\ inch in length and 

 1 inch in diameter. 



The pectinations of the branchial plume of nearly all the 

 Littorince, instead of being 16-20, vary from 45-60; they are 

 pale brown, long, slender, and close-set; an examination 

 under the microscope sanctions this correction. Having re- 

 peated a series of fresh observations on some hundreds of the 

 Littorina rudis in comparison with the L. tenebrosa and 

 L. jugosa of authors, I am authorized to say, that the identity 

 in figure and action of their internal and external organs has 

 further satisfied me of the propriety of regarding them as 

 varieties of the L. rudis ; the onlv differences arc colour and 



