60 



all parts of the globe, being most numerous, of larger growth, 

 and more beautiful color in tropical seas. The shells of the 

 Trochidce, though formed on one type, assume a great variety 

 of contour and sculpture, being turbinate and provided with 

 stony opercula in some (PJiasianella) , cancellated and 

 discoidal with horny calcareous opercula, in Liotia conical 

 or pyramidal with horny multispiral opercula in Trochinse, 

 with the opercula uniting in Stomatellince, which section 

 gradually leads to the Haliotidce, in which the branchial 

 plumes are symmetrical, the muscle of attachment is central, 

 and the mouth is fissured in front. 



Sub-family Eutropin^. — This family is erected for one 

 genus of which our PJiasianella is the type. Messrs. Adams 

 insist on giving the name of Eutropia, because that was the 

 one first applied by Humphrey. In answer to this it must 

 be noticed that Humphrey is not entitled to priority, as he 

 published no definition of his genus. Secondly, Lamarck's 

 name is generally received and adopted by conchologists and 

 by geologists. It is not at all likely that the latter would 

 ever consent to the change, and Continental naturalists have 

 refused to receive it. Confusion, therefore, would only 

 result from following Messrs. Adams or Mr. G. F. Angas in 

 this matter. 



The second sub-family is Turhinincs, including turbinate 

 shells with the last whorl ventricose, aperture sub-circular, 

 inner lip smooth and simple. Operculum horny, with a 

 solid, convex, calcareous coat. 



Genus Turho, Linnaeus. — This is one of the oldest genera, 

 dating back as far or as early as Eondel (Universse aquatilium 

 historise, pars altera II., Lyons 1554), but has undergone so 

 many changes and revisions that even the definition of 

 Linne in his revision of the genus he first made would no 

 longer apply to it. It is restricted by Messrs. Adams to 

 those turbinate shells with a smooth or granular operculum, 

 but without spiral ridges. Senectus and Lunella are made 

 into separate genera, together with Ninella. The first is 

 distinguished by the variegated colors and ribbed whorls. 

 It is a genus of Humphreys, which is adopted by Swainson, 

 and is said to be the equivalent of Bol ten's Lunatlca (Museum 

 Boltenianum ? 1798*) and Schumacher's Batillus. Chenu 

 only admits it as a sub- genus, and as such only I think it 

 should be retained in our only species (T. Senectus) circularis, 

 Eeeve. 



Lunella is a genus of Bolten's. Messrs. Adams include 

 our Turho undulatus Chemnitz in this genus, but it has a 



*A second edition of this work by J. Noodt was published in Hamburr 

 1819, with two plates. 



