July ], 1869.] 



HARDWICKE'S SCIENCE-GOSSIP. 



159 



testifying to the constant presence of the mud, 

 thinks it probable that it is taken involuntarily 

 with its other food, whatever that may be. In a 

 translation of Louis Eiguier's entertaining summary 

 entitled "The Insect World," published in this 

 country last year, it is correctly stated that this 

 larva feeds on small insects ; but no authority is 

 quoted, and the mud question is not stirred. 



My acquaintance with the Ephemera was made 

 accidentally some years ago. Dipping for Daphnire 

 ;tnd other small crustaceans, an advanced larva, or 

 pupa, of Ephemera vulgata was included in the 

 capture, and all together transferred to a small 

 aquarium. In a fortnight afterwards not a water- 

 flea was left. The pupa, quivering with excitement 

 from head to tail, swooped with unerring aim on 

 the doomed crustaceans, so long as any were left, 

 and he felt an appetite. A second supply was 

 given, and shared the like fate ; and now the 

 growth of the pupa was completed. One fine May 

 morning the graceful .fly was found in the window ; 

 from which it escaped into the open air. 



It had left three or four exuviae, thrown off from 

 time to time, and one of these, perhaps the last, 

 exhibits, when mounted in balsam, a perfect 

 impression of the mouth, and may throw some light 

 upon the nature of the food. The jaws, when 

 open, form a wide funnel for the more ready 

 capture of a nimble prey ; when closed, they seem 

 designed to interlace each other and form a 

 compact front to bar all escape. The teeth exhibit 

 a row of slightly curved bars on one side, opposed 

 on the other to a raised block, crowned with sharp 

 serrated edges, and could be brought together with 

 crushing effect on the poor little crustaceans. The 

 back of the mouth is partly closed by a singular and 

 curious contrivance ; a deep egg-shaped sac 

 extends across it, opening into the throat by valves 

 or slits, fenced on the outside with fine hairs, which 

 would permit the downward passage of a too lively 

 Daphnia, but prevent its return. And here we 

 may probably account for] the constant presence 

 of mud in the intestinal canal. A mouthful taken 

 involuntarily in a struggle at the bottom with a 

 lively prey and swallowed with it, would be 

 retained by the fine sieves across the valves of the 

 throat and pass into the stomach. Such a condi- 

 ment might be even beneficial (for all such contin- 

 gencies are weighed) by dividing the food, or, as 

 seems very likely, by increasing the gravity of the 

 body after a meal, and so enabling the larva to 

 remain without effort at the bottom. My aquarium 

 contained no mud, yet the pupa throve well ; but in 

 streams and eddies it might be difficult for so light 

 a creature, furnished with a large breadth of 

 branchial plates, to maintain its place or remain in 

 concealment, without ballast ; or it might be useful 

 in other wavs which we cannot even guess. 



S. S. 



THE LEPIDOPTEPJST'S GUIDE.* 



~]\/rANY a time and oft have we been solicited to 

 -"-■- name a book for the use of those who have 

 no knowledge whatever of the art of rearing, catch- 

 ing, or preserving insects. Through nearly all 

 orders this query has traversed, but ofteuest has it 

 related to the Lepidoptera alone, and the editorial 

 murmur has been little other thau a grumble in 

 reply. At length a light has broken upon us, and 

 we rejoice in the prospect of a happier future. Let 

 any one now inquire for a guide, and we have an 

 answer ready; one which we have had serious 

 thoughts of keeping permanently in type, or stereo- 

 typing : it is— the title of the book announced at 

 the foot of this page— Dr. Knaggs's " Lepidopter- 

 ist's Guide." The author is just the man, of all 

 others, we should desire for a cicerone, and so 

 would all who seek the service he proffers, As oue 

 of the editors of the Entomologist's Monthly Maga- 

 zine we may at once take it for granted, without 

 any further assurance that the science of the book 

 is all right, that the subject is treated by a practical 

 hand, and one well up to the work. But that is 

 not all, there is another recommendation, and a 

 very strong one with our readers,— the author has 

 such a happy knack of popularizing his subject, so 

 facile in saying a plain thing iu a plain way, so clear 

 in his instructions, so hearty and enthusiastic in 

 his work, that any one would wish himself an ' 

 ignoramus again to have the pleasure of such a 

 teacher. In these days of compiling, and book- 

 making, and dealing freely with other men's brains, 

 your reviewer can hardly resist the temptation to 

 become enthusiastic when he encounters a book 

 that is really original, and, like the present, a reflex 

 of the author himself, and his own flesh and blood 

 experiences. 



Let us briefly scan the book itself, and see what 

 its closely but clearly printed one hundred and 

 twenty pages contain. It is a " Lepidopterist's 

 Guide," all about moths and butterflies that the 

 inexperienced collector wants to know. Of course 

 some of the hints and methods are everybody's pro- 

 perty, but the author in the preface cautions the 

 reader against supposing that all comes out of his 

 own head, and he has no desire to appropriate what 

 does not belong to him. He gives old or well- 

 known methods, whenever he has no better of his 

 own to offer, or no better are needed. The little 

 bits of fun which sparkle here and there is not the 

 sort of thing for us to condemn. We do not think 

 that because a writer deals with scientific subjects 



* The " Lepidopterist's Guide," intended for the use of the 

 young collector, containing full instructions for the collect- 

 ing, management, observation, and preservation of Lepi- 

 doptera in all their stages. By H. Guard Knaggs, M.D., 

 F.L.S, London : Van Voorst. 



