A HISTORY OF NORTHAMPTONSHIRE 



teen segments is partly free and slightly mobile. At the base of the 

 outer antenna in the crayfish there is a large flat hair-fringed scale, in 

 place of which the lobster has only a small spike. Less obvious, but not 

 less important, are the differences in the branchiae or gills. Those known 

 as podobranchis have the stem longitudinally split in the lobster but 

 not in the crayfish, and of the so-called pleuro-branchix some are 

 rudimentary in the crayfish which in the lobster are well developed. 

 Further details might be added, but these are enough to show that in 

 natural history a hasty glance will not always safely determine genera and 

 species. 



Around the technical name of the crayfish a certain amount of 

 controversy still hovers. Huxley himself begins his book by calling 

 our English species Astacus Jiuviatilis, but ends by calling it, though with 

 some reserve, Astacus torrentium} Dr. Walter Faxon, an American expert, 

 decides that our species should be named Astacus pallipes? But, what- 

 ever may be right for the second name, I personally am convinced that 

 the first or generic name is properly Potamobius, and practically Huxley 

 supports this view by placing it in the family Potamobiidce, the name of 

 which can only be sustained by upholding the genus Potamobius for the 

 English crayfish.^ 



The gastronomic value of the species has long been recognized. 

 Its educational value is now even more highly appreciated. Both this 

 and its claim to belong to the fauna of this county are attested by the 

 following quotation. Mr. Beeby Thompson, F.C.S., F.L.S., of North- 

 ampton, writing in December, 1886, says : — 



' Several crayfish were recently required for dissection at the Science 

 School, and one of the students undertook to procure them. The speci- 

 mens were obtained from a shallow part of the river [Nene] near St. 

 Andrew's Mill. I know that Cray-fish or Caw-fish [.? misprint for Craw- 

 fish], as they are commonly called, have been found at this spot for thirty 

 years, but I never saw them or heard of them being found at any other 

 place near Northampton. Perhaps some of our members can give informa- 

 tion as to other localities that they inhabit. I for one should be glad to 

 know of such. I may say that two of the specimens caught last May have 

 been in my aquarium ever since, and seem now to be in good condition. 

 They are most interesting animals to watch ; the way in which they 

 seize and devour minute joints of meat shows that they are not altogether 

 free from the occasional human feeling of selfishness. Each of the cray- 

 fish has shed its skin once since it became an inhabitant of the present 

 restricted abode. To see one of these crustaceans shed its covering is 

 one of the things I am still desiring ; it seems marvellous how they can 

 get out of it so as to leave such a perfect case of themselves. They 

 appear to hide themselves under the stones much more about the time of 

 shedding their covering, and particularly after it, than at other times. 



* The Cra^^sh, an Introduction to the study of Zoology, International Scientific Series, vol. xxviii. 3rd 

 ed. p. 296 (1881). 



' Proceedings of the /American Academy of Arts and Sciences, vol. xx. p. i 54 (1884). 

 ' Annals and Magazine of Natural History, ser. 6, vol. xix. p. 1 20. 



102 



