HARD WICKE'S SCIENCE- G OS SI P. 



19 



themselves, out of the grass stems upon which they 

 feed, of an extraordinary character, looking much 

 like the cases of caddis worms. It appears that the 

 Caffirs regard the swallowing of one of these grubs 

 by any ox that may be feeding on the grass where 

 they live, as certain death to the poor ox. Within 

 certain limits, upon the table before him, Mr. Lewis 

 •allowed these curious grubs to trot about, and they 

 yielded no end of interest to the observers. Then, 

 there was the pupa of a cat flea, showing, apparently, 

 that the statement Mr. Lowe makes in his monograph 

 of the anatomy, &c., of the blow-fly, that "all the 

 tissues of the larva undergo degeneration, and the 

 imaginal tissues are re-developed from cells which 

 ■originate from the disintegrated parts of the larva," 

 (page 116), holds good as regards the flea also. 

 Mr. Michael told me that this view is pretty generally 

 accepted by scientific people, as applying to all, or 

 ;almost all, insects. Well, it may be ; but I know 

 one person, claiming to be thoroughly acquainted 

 with all that is worth knowing about insects, who 

 smiles incredulously when I talk to him of this fact. 

 Mr. Michael had on view a very beautiful dissection 

 •of a small Staphylinus. The Rev. T. King showed 

 two fine specimens of flies in amber under his 

 microscope. How many thousands of years had they 

 been entombed there ? Ah ! and yet they are as 

 ^^erfectly preserved as if they had been done up in 

 balsam only yesterday. Several Fellows had re- 

 markable specimens of foraminifera, &c. Mr. Priest 

 showed tiie inner casts of some of these organisms. 

 There was also a living spider exhibited by Mr. R. 

 Facer, showing the action of the spinnerets. Mr. E. 

 J. Smith showed numerous fine sections of rare 

 minerals, and Mr. Suffolk, a scale oi Morphomeiielaiis, 

 under very high magnification. —3". J. Mclntire. 



Frontal Sac of the MusciD.t:.— The author of 

 this important paper is Mr. W, Jenkinson, of the 

 Sheffield Microscopical Society. 



ZOOLOGY. 



Anodonta Cygnea.— Ml". Roberts seems to have 

 •expected me to have replied to some strictures made 

 by a correspondent on my paper, entitled "A Day's 

 Shell Collecting," which was published in SciENCE- 

 GossiP last year. I had already virtually replied in 

 my article, since I cannot class Mr. Webb with 

 anyone else but Dr. Woodward for his knowledge of 

 what constitutes a species and a variety. I scarcely 

 then thought it worth my trouble, and I had not now 

 said anything had not Mr. Roberts again opened the 

 subject, especially, as Mr. Webb so well defended 

 the points that ruffled him as to decry with all his 

 force the " variety-mongerers," and at the same time 

 want to make a variety of a species, a point of 

 impudence which I may say they have never reached. 



In point of fact, Mr. Webb's ambition seems to me 

 that of becoming a king, as it were, for his good 

 works, among the race of conchologists whom he 

 apparently so heartily despises. I can but refer 

 Mr. Webb, since I am not going to occupy your 

 space in teaching the elementary principles of 

 zoological nomenclature, to one of the more modern 

 zoological text-books, as Claus, for example, in order 

 to give him more definite ideas as to what constitutes 

 a species and what a variety- Mr. Roberts has very 

 rightly remarked that "Dr. Woodward and a few 

 other antediluvians . . . might as well argue that all 

 the species of continental anodons are one, and that 

 Unio tu /nidus, Uiiio pidortim, &c., are all one," and I 

 might add to these all the Pisidia too, and Limuixa 

 pcregra, and LimncEa aitricularia also. I am here 

 again only going to make the dogmatic assertion, that 

 A cygiica differs in its anatomy very essentially from 

 A. anatina. I am not going to state these differences, 

 since I shall doubtless publish on them before long 

 in " The Journal of Conchology." But, in the 

 meantime, Mr. Webb can easily dissect one or two 

 for himself, and then when he has gained a scientific 

 knowledge of what he is talking about we shall be 

 pleased to hear from him again, A personal know- 

 ledge of a subject from actual work is of far greater 

 value than raking up a host of old authorities, 

 Mr, Webb. Had you been a little more modern, you 

 would have known that on p. 65 of the fifth volume 

 of " The Annals and Magazine of Natural History," 

 Mr. Lloyd described some anatomical differences 

 between Anodonta cygnea and A. anatina. — y, IV. 

 Williams. 



Anodonta Cygnea, Linne. — Mr. George Roberts 

 appears to forget that opinion, however weighty, is 

 not evidence ; and that authorities were quoted in 

 my note not to prove that Anodonta anatina was a 

 bad species, but to show that a statement to such 

 effect could not rightly be called an " uncanonical 

 assertion." Again, the fact that earlier conchologists 

 confounded together two species of Helix is no 

 argument whatever that they also confounded two 

 species of Anodonta. The point in question depends 

 upon the recognised meaning of the word Species. 

 Zoologists and botanists of the present day know 

 perfectly well that there is naturally no strict line of 

 demarkation between closely allied forms which they 

 place together and call a Genus ; but, for convenience 

 in classification, the name species is kept by them to 

 denote a form which can be separated from its rela- 

 tions by well-ascertained anatomical diff'erences. 

 Unfortunately, there are many shell-collectors who 

 do not know this, and the few that have mastered it 

 no more understand why and for what the term 

 "variety" was instituted than the mass of their 

 brethren do. The reason is not very doubtful, for 

 these collectors follow Uke sheep the precepts of 

 certain Continental and the Leeds schools, which 



