228 POPULAR BRITISH CONCHOLOGY. 



followed by 'Proctonotus mucroniferus, with its pyriform, 

 tubercular gills, arranged in twelve rows of three each ; and 

 Antiopa sjdendidula, with a crest between the hinder ten- 

 tacula. 



The green Hermia dendritica does not differ much in 

 appearance from Eolis, but has the vent on the anterior 

 part of the back ; H. bifida is the name of the other species. 



Coming now to the few remaining genera which, in ap- 

 pearance at least, bear a great resemblance to the land-slugs, 

 we find the external manifestation of breathing apparatus 

 gradually lessening, till it assumes a. totally different cha- 

 racter. Thus, in Alderia modesta the gills consist of a 

 single row, on each side, of simple papillae; in Biimina 

 Rancocki they are three small plumes near the vent ; while 

 in the species composing the family of Eli/siadce, namely 

 Limatopontia nigraj Blysia viridisy Actceonia corrugata, and 

 Coenia CocJcsii, the breathing operation is performed over 

 the whole surface of the body, by means of minute, vibrat- 

 ing cilia. 



With the interesting account of one of these, the Mysia 

 viridu'j or, as it is more generally called, the Green Actseon, 

 from the pen of the author of the ^Natural History of 

 Arran,' we must conclude our notice of this order. 



