256 FISSURELLIDJE. 



extent enables us to dispense with the so-called science 

 of malacology. The fewer technical words that are 

 used, the more easy it will be for students to learn the 

 language of this or any other branch of natural history. 

 The tubular process of the mantle apparently serves for 

 the admission of aerated water to the gills, as in the 

 Siphonobranchiata ; it has been also, but without reason, 

 supposed to have a faecal office. The outer layer of the 

 shell is laminated, the middle one cellular, and the 

 inner nacreous. None of the Fissurellidce can properly 

 be called littoral, although some of them are occasionally 

 found under stones at low-water mark. They are spread 

 over all parts of the world. 



Genus I. PUNCTUREL'LA *, R. T. Lowe. 

 PL VI. f. 2. 



BODY conical : mantle protruded through a slit near the 

 top of the shell on the anterior side, outside of which it forms 

 a short tubular process : foot crested with a row of papillae. 



SHELL cap-shaped, with a slit in front of the crown : beak 

 always spiral: inside furnished with a short funnel-shaped 

 process having its exit in the hole abovementioned. 



The name Cemoria, proposed by Dr. Leach, was not 

 published before Mr. Lowe described the present genus ; 

 the type of the first-named genus is the fry of Fissurella 

 Graca. The Cemoria of Bisso (from Leach's MS.) is a 

 fossil, and apparently a species of Calyptrcea. Some 

 conchologists have associated Defrance's genus Rimula 

 with that of which we are now treating : the latter has 

 an internal process, and the perforation is placed close to 

 the crown ; while the other has no such process, and the 

 perforation is placed midway between the crown and the 

 posterior margin. Rimula bears the same relation to 

 * Having a small prick or puncture in the shell. 



