A. S. Packard, Jr. on certain Entomological Speculations. 200 



ON CERTAIN ENTOMOLOGICAL SPECULATIONS.— A REVIEW. 

 BY A. S. PACKARD, JR., M. D. 



Tn the Proceedings of this Society for August, 1864, Mr. B. P. 

 Walsh, in the course of his remarks '• On certain Entomological 

 Speculations of the New England School of Naturalists," discusses 

 snine points of common interest to all zoologists. 



The discoveries of embryologists proving that the winged insect, 

 in the course of its growth, successively passes through stages (the 

 larva and pupa) which are analogous in form, to the adult state of the 

 Worm and Crustacean, respectively, are ridiculed by our author as a 

 matter of pure fancy. Oken in 1821 said. " Every fly creeps as a 

 worm out of the egg; then, by changing into the pupa, it becomes a 

 crab, and lastly, a perfect fly."* 



These words it remained for Yon Baer+ to prove, when in 1828 he 

 laid down the general law of embryology, that all animals in starting 

 from the egg state, must, in order to reach maturity, pass through 

 forms which resemble the adult state of those beneath them in the 

 scale of life. The subject is abundantly enforced in mauy receut 

 works, especially those of Rathke, Newport. Miiller, Agassiz, Milne 

 Kdwards, Pana. and others, and is so familiar to the well-informed 

 naturalist, that it need not detain us farther. 



In the first place, Mr. Walsh disputes the statement that the larva of 

 an insect is like a worm, considering the phrase "worm-like" as '-loose 

 and indefinite." Put what is a worm ? Our author provides us with no 

 definition. We are simply led to infer from a paragraph on page 233, 

 that every worm must be necessarily more than twice as long as broad, 

 as he states that the larva of Limacodes. which is elliptical in shape. 

 is • anything but worm-like." Hence our author consigns to oblivion 

 all those members of the class Vermes which do not come up to his 

 mathematical standard of what a worm ought to be. He rejects from 

 his rolls every unfortunate Annelid which is not more than twice as 

 long as broad. 



It would appear as if Mr. Walsh had before him a figure of the 

 ■ earth-worm, a very long, cylindrical and slender-bodied form. This 

 we admit to be the typical form of the class. Put this form will not 

 answer as a guage for the entire class. 



Where would he place in his New System of Annelids, such obsti- 



Naturgeschichte fur Schulen, p. ."> 7 7 a- quoted by K. Owen. Lectures on 

 ■ omparative Anatomy ami Physiology of the [n vertebrate Animals. Lon- 

 don. 1st::, p. 24 7. 

 t Oeber Entwickelungeschichte, etc. Theil, I, p. 230. 1828. 



PROCEEDINGS ENT. -■•«'. 11I1LAD. NOVEMBER, 1866. 



