76 



THE PRACTICAL ENTOMOLOGIST. 



In Crustacea the standard of size would seem to 

 be reversed, but the principal of cephalization, or 

 concentration of parts headwards is more marked 

 here than in insects. While in Insects the lu-ad is 

 largest, in Crustacea the thoracic region is most de- 

 veloped, while in Worms the abdomen is largest, and 

 the largest worms are highest in the scale. 



In ascertaining the minor divisions of the insects 

 we must keep in full view the principle of articu- 

 lation and the relations of the rings to themselves 

 and their mode of grouping, and not consider as of 

 primary importance the appendages, which now first 

 come into consideration. We shall find that all the 

 minor divisions, or orders, sub-orders, families and 

 genera, and even species, ai-e but a more special work- 

 ing up of the primary principle of classification — 

 which determine rank and group — and are all but 

 modifications of an ideal form, becoming more special 

 as the group becomes more limited, or smaller. As 

 we approach species represented by the individiinJ, 

 slighter diiferences separate them, and are even ap- 

 parent among individuals, enabling us by changes 

 in form and ornamentation to detect differences be- 

 tween persons. No two individual insects can be 

 found exactly resembling each other, just as no two 

 men can be found to be precisely alike. 



BESCRIPTION OF THE FIGURES. 



Fig. 1 represents an ideal section of a Worm. / 

 indicates the skin or muscular body-wall, which in 

 each side is produced into one or more fleshy fila- 

 ments tipped usually with bristles or hairs, which 

 serve as organs of locomotion, and often as lungs. 

 The nervous cord (a) rests on the floor of the cylinder, 

 sending a filament into the oar-like feet (/) and 

 also around the intestine or stomach (6) to a sup- 

 plementary cord (r/) which is situated just over the 

 intestine, and under the heart or dorsal vessel (c). 

 The circle c and e is a diagram of the circulatory 

 system; c is the dorsal vessel or heart, from the side 

 of which, in each ring, a small vessel is sent down- 

 wards and around to c, the ventral vessel. So tliat 

 the circulation is a closed one in the higher worms, 

 as well as the Crustacea'^nd Insects. 



Fig. 2 is an ideal section of a Bee. Here the 



crust i§ dense and thick, to which strong muscles 

 are attached. On the upper side of the ring the 

 wings grow out, while the legs grow out near the 

 under side. The tracheas ((/) enter through the 

 stlijnia or breathing pore, situated just under the 

 wing, and its branches sub-divide and are distri- 

 buted to the wings, with their five principal ner- 

 vures as indicated in the figure, also to the dorsal 

 vessel (f) the intestine ( Ij) and the nervous cord (a). 

 The two circles seen in fig. 1, representing the course 

 of the blood vessels and nerves, are here left out so 

 as to avoid confusion. The tracheae and a nervous 

 filament are also sent each into the legs and wings. 

 The tracheae also are distributed to the dorsal vessel 

 and intestine by numerous branches. A. S. P. 



ITote on Black-Knot. 



BY EEXJ. D. WALSH, M. A. 



In my article on Black-knot in No. 6 of the 

 Practical Entomologist I incorrectly stated 

 that the' fungus growing on its surface is about the 

 size of the head of a pin. It is only when seen 

 through a pocket microscope that it appears so large 

 as the licad of an ordinary toilet pin. When viewed 

 with the naked eye it is scarcely larger than the 

 point of a dull-pointed pin. 



J6®" Membership in the Entomological So- 

 ciety OF Piiiladelphi.\. — Any person may be- 

 come an Honorary Memher of the Society, upon 

 the payment of a sum of not less than One hundred 

 dollars ($100) for the benefit of the Publication 

 Fund ; and any person may become a Contrilniting 

 jMemher, upon the annual payment of a sum of not 

 less than One dollar (-SI). 



B@° Honorary and Contributing Members have 

 all the privileges of Resident Members, except 

 those of voting and holding ofliice. 



JU®" Handsome Diplomas are furnished free to 

 all Members. 



ACKNOWLEDGMENT. 



We thankfully acknowlodge tlio receipt of Three dol- 

 lars from Mr. 0. II. Peck, of Massachusetts, for this Paper. 



