IS NASSA. 



round pellet; under tiiis tin- creature conceals itself. The fry 

 twist :ni(l twirl about by means of their ciliated lobes. X. 

 ntiit.ahil.iK is an article of food in Italy. The generic name is 

 that of a narrow-necked wicker basket used for catching tish, 

 and in such a basket, lobster pots, etc., the Xasxa- itself is 

 tVe;|iiently caught, attracted thither by odors .savory. 



NaNwi. rc/iculata is said to be very destructive in the oyster 

 pares of A reaction (S. of France). It is so numerous that a 

 single tide lias yielded 14. GOO specimens within a space of 40 

 French hectares (= about 100 acres). The adult Naasa will 

 bore through the shell of an oyster three years old, within eight 

 hours ; but the young shells are far more destructive because 

 they select the tender shells of the very young oysters, some- 

 times piercing iifteen or twenty in succession before their 

 hunger is satisfied. An oyster a month old is destroyed in a 

 half hour.* 



One of the best students of the genus iVassa is undoubtedly 

 Mr. F. P. Marrat. of the Liverpool Museum. f Imbued with 

 extreme development views he has, unfortunately, adopted the 

 principle in his scientific work that, the variations of specie^ 

 being illimitable species in fact, as usually defined, being non- 

 existent, the naturalist may apply a spec! tic name for each 

 modification of form, sculpture or coloration ; a principle the 

 absurdity of which must be apparent when it is considered that, 

 no two shells being exactly alike, it will, admit of the description 

 of every individual specimen as a " new form." Mr. Marrat has. 

 however, fully demonstrated the insufliciency of distinctions 

 based on sculpture in a number of species of the genus; a result 

 most confusing to the sv steniatist . and which leaves the validity 

 of many forms described f 'rom single or few specimens very 

 <iuestionable. I am tempted to make some extracts from Mr. 

 Marrat 's latest p:iper,; the subject of variation being sufficiently 

 important in a general sense t > j-.istify me iu devoting n few 

 lines to its illustration in this particular genus. 



* Soubeiran, Bull. S<><;. <l' Acclimatation, 2 Ser., iii, o, I860. 



f "On the variation of sculpture exhibited in the shells of the genus 

 Nassa." "On forty proposed new forms in the genus Nassa," etc. 



J " On the Varieties of tho Shells belonging to the gonus 



