INVERTEBRATE ANIMALS. 37 



Group 106. Family PLEUROTOMID^. TrXsvpa, side; 

 To'iaoj, a notch. Estimated number of species : recent, 

 491 ; British, 15 ; fossil, 300. Cretaceous, &c. 

 Murchisonia iMcata, Higgins and Marrat. 

 II Examples of Plenrotoma = Tmris, Mangelia, &c. 

 Large number of generic forms. 



Family MURICID^. Mnrex. 



Group 107.— Sub-family FUSIN.E. fusus, a spindle. 

 Estimated number of species : recent, 206 ; British, 6 ; 

 fossil, 340. Oolite, &c. 



^ Examples of Fiisus, Hemifusus, Pisania, 

 Neptunea Turtoni, &c. ; amoust them, Ftisus 

 pagod'iis and Metula clathrata. 



Upper Compartment. 



Fusus antiqiius, fitted up as in Norway for use as a 

 lamp. 



Group 108.— Sub-family MURICIN^. Estimated number 

 of species: recent, 268; British, 5; fossil, 180. 

 Chiefly Tertiary. 



II Examples of Murex, Trophon, &c., including a 

 very fine series of Typhis, S. Smith ; and 

 Murex endivia, Dennison collection. 

 Murex imhricatus, Higgins and Marrat. 

 M. brandaris and M. erinaceus were probably the 

 chief sources of the purple dye for which 

 ancient Tyre was celebrated. 



1)1 the 2IoUiiscs of the next Sub-class occur for the first time in the ancendinfj 

 series aniniah which have attained to aerial respiration. As compared 



