216 A. S. Packard. Jr. on certain Entomological Speculations. 



and 234, does Mr. Walsh in self-contradiction of his main proposition, 

 tacitly admit that most lepidopterons larvae, and some coleopterous lar- 

 vae, are worm-like, even according to his mathematical definition of a 

 worm. The apparent exceptions to a typical worm-like form are, then, 

 no violations of a general law. 



The idea that the pupa of an insect hears a resemblance to a 

 Crustacean, is combatted with much vigor. Mr. Walsh states that in 

 the pupae of most insects, namely, in the " Lepidoptera, Hymenoptera, 

 Coleoptera, Diptera and the true Neuroptera . . . the head is con- 

 nected with the thorax by a very distinct connate suture, and in many 

 Coleoptera, especially Tetramera, and most Hymenoptera and Neurop- 

 tera, there is, in addition, a very distiuct constriction or neck at this 

 suture, thus offering not the faintest resemblance to the Crustacean 

 Cephalothorax," p. 235. 



In the sentence preceding that from which this quotation is taken, 

 we are informed that a Crustacean differs from an Insect in having a 

 "head soldered to the thorax without any sutures." We cannot right- 

 ly conceive of a "head" in distinction from the rest of the body 

 among the Crustaceans. The researches of Rathke on the Development 

 of Astacus, and the statement of Prof. Dana* that the development of 

 the cephalothorax proceeds from a single centre, show plainly that there 

 are in this class but two centres of development, i. e. the cephalotho- 

 rax and abdomen. 



In the pupa of the Mosquito, Corethra, and allied genera, where the 

 head is closely united with the large thorax, we have the strongest re- 

 semblance to some of the Stomapods and young Decapods, and especi- 

 ally the Amphipodous Hyperia, and if such comparisons as these seem 

 too vague and remote, we would inquire what are Analogies and lie- 

 semblances in nature, if these striking recurrences of homomorphous 

 forms are not? We would remind our author of his owu quotations to 

 this effect from Latreille, (p. 244), that "Nature seems to work after 

 a certain limited number of patterns, which she reproduces with modi- 

 fications in widely distinct classes and orders," which is quoted with 

 much satisfaction, when our writer discourses on the origin of his 

 •■ Phytophagic species." Latreille's statement that an insect may 

 resemble class-forms, quite remote in their natural scries, is discarded 

 when our author scouts one of the prime laws of animal growth ; but 

 is adopted most illogically when he so glibly talks of the origin of his 

 so-called " species." 



The general analogy of the pupa of Insects to the Order of Aiaeh- 



* Crustacea of the I". S. Exploring Expedition. 



