300 



THE AMERICAN 



that eauh successive pair of legs is more aud more marked 

 with blacli. In Ephemeridai, on the contrary, the front pair 

 of legs is normally by far the darkest, the four hind legs 

 being nearly alike in their coloration. And so with other 

 families of insects— each will be found to be marked accord- 

 ing to certain general colorational laws. Why, if it be the 

 correct doctrine that every species was independently cre- 

 ated, the great Author of Nature should have restricted him- 

 self, in the case of each family, to certain definite colorational 

 patterns, is a mystery which I have never yet been able to 

 solve. Neither do those who still cliug to this almost ex- 

 ploded doctrine make the least attempt to solve this insoluble 

 enigma, but, in the words of Mr. Wallace, are content to 

 ' ' register the facts and wonder. ' ' 



Eurytoma gigantea, n. sp. $ Black. Head snbopaque, 

 conlluently and very coarsely punctate, and with short 

 whitish decumbent hairs. Antenna: 9-jointed, the joints 

 proportioned to each other as 14, 3, 6, i), 5, i, i, 4, B, the flag- 

 ellar joints longer than nsual in proportion to their breadth, 

 the penidtimate joint being ]J times as long as wide. ■Thorax 

 sculptured as the head, but still more coarsely. Abdomen 

 polished and glabrous but a little hairy towards its tip, more 

 comviressed than usual, and with the usual flue i>unctation 

 on the ."ith or long joint extending almost up to the dorsal 

 line. Ventral valve unusually long and acutely ]iorrect. 

 J/Cgs black, the knees and the tips of the tibia:, and in the 

 front legs the entire tibia;, all honey-yellow; tarsi, except 

 their extreme tips, whitish, the anterior tarsi pale honey- 

 yellow. Wings hyaline; veins honey-yellow. Length 2 

 0.19-0.25 inch. 



Described from 2 g captured at large; ^ unknown. By 

 far the largest species that I have seen, aud readily distin- 

 guishable by the 9-jointed antenna;, the suture between the 

 Sth aud 9th joint being as distinctly a free suture as any of 

 the others . 



GENUS DECATOMA. 

 St/noptical table, to find the species described below. 

 A — A di=tiiict stiginatic dark band on the front wing. 

 a. Body muslly black. 



1. Head mostly pale 



2. Head entirely black 

 6 Bod.v almost entirel.v pale 



li~ — No slif^inatic dark band, 

 a. Body mostly black 

 6. Body almost entirely pale 



- nubilistig:ma, n. sp. 



Decatoma varians, n . sp.— |-^ § (Fig. 2) pale ochre-yellow 

 ranging tlirough honey-yellow to rufous. Head subopaque, 

 conlluently and very coarsely punctate. A black spot on 

 the vertex, sometimes uotTextending beyond the ocelli, some- 

 times covering the whole vertex, and very rarely (1 § spring 

 brood, 1 g autumnal brood) extending over the superior 

 half of the occiput. Antenna: rauging from i>ale honey- 

 yellow to rufous, the flagelltmi very rarely (1 ^ spring 

 brood, 1 c^ autmnnal brood) brown-black above. Thorax 

 sculptured as the head, but still more coarsely, coUare 

 generally either inniiaculate or with only a basal black band, 

 rarely with a subcpiadrate black patch covering the entire 

 superior surface, aud sometimes with only the lateral and 

 basal limits or this patch black. Mesonotum and metanotum 

 black, generally with the sutures and the entire ])ostscutellar 

 triangles of the jnesonouun (Fig. 8, B, rf) yellow or rufous. 

 Pleura usually immaculate, i-arely a little varied with black. 

 Abdomen highly polislied, with the peduncle (^ nearly -'j as 

 '"ig, 2 1-.5 as long as the rest of the abdomen ; (^ $ black 

 with the peduncle, two or three of the basal joints and the 

 venter often more or less piceous or rufous or honey-yellow; 



in one rf the entire abdomen, except a dorsal black patch 

 behind, being honey-yellow. Legs rarely immaculate, 

 usually with an abbreviated, narrow black superior vitta on 

 the femur, which becomes wider and longer in each succes- 

 sive pair of legs, and occasionally in the hind femur covers 

 the whole of it except the extreme b.ise and tip ; tibiae the 

 same, but the front tibije are almost always immaculate, 

 and the hind tibice are generally black throughout except 

 their extreme base and tip; coxa: and trochanters immacu- 

 late, but the hind coxa: are more or less widely vittate or 

 bivittate with black tibovc, e,^cept their extreme base and 

 tip. Wings hyaline; stigma black, veins and stigmatio patch 

 brown-black, the latter extending r^ of the way across the 

 wing, and almost always widened behind so as to appear 

 bottle-shaped, the stigma forming the neck of the bottle. 

 Length (j* 0.09—0 14, g 0.10— 0.10 inch. 



Described from 2(i |^ Z.? g , th.at came out from the Cyiii- 

 pidous oak-gall Q. podogrte, Walsh, of the same year's 

 growth, September 4th— Oct. 11th, and 6 (5" 2 $ that came 

 out from the same gall, only of last year's growth. May 21st 

 —June 21st. From the Cynipidous oak-gall Q. spongifica, O. 

 S., I have obtained 1 cj 7 g , dilfering in no respect from 

 those produced by the other gall (Q podagras) , except that 

 they varied in size still more remarkably, the (J' being only 

 07 inch aud the largest g as much as 0.16 inch long. From 

 the allied oak-gall , Q. in anis, O . S , I bred a single |-J" of aver, 

 age size aud coloration . A single rather small g , bred from 

 the Cynipidous oak-gall, Q. paluslris, O S., growing either 

 on the Black or Laurel Oak, has the ocoiptit black above and 

 the antenntc brown-black above; but it is otherwise normally 

 colored. I possess also 2 jj 1 g captured at large, that do 

 not differ from the normal form. This is an exceedingly 

 variable species, both as regards size and coloration. 



Variety dubia, ^ g .— This form differs fiomD. varians 

 only as follows: Ist. The average size is much larger. 

 2d. The coloration is darker, nearly the entire occiput, and 

 the entire face except the antennal groove and the anterior 

 border, the entire mesonotum including thepostscutellar tri- 

 angles, (Fig. S, 15, d), almost the entire pleura, and the en- 

 tire .abdomen, being black. 3d, The stigmatic dark band is 

 never bottle-shaped, but is of the same width as the stigma 

 throughout. Length jj 0.15, g 0.16 inch. 



Described from 1 ,^ 5 g , bred May 21st— 29th, from the 

 Cynipidous Oak-gall Q. mamMH, Walsh MS., of the preceding 

 year's growth. This gall, it should be observed, grows not 

 only on a different species of Oak (Burr Oak) from those on 

 which the galls producing n variatis grow (Black, Ked and 

 Laurel Oaks), but also on a species belonging to a distinct 

 subdivision of the genus. Out of a total of 32 (f" 27 g of D. 

 varians, bred from the gall of Q. podagra, but 3 g , measuring 

 0.10—0.15 inch, agree with the form dubia. 



Decatoma nigriceps, n. sp.—(f g differ from the normal 

 form of D. varians only as follows; 1st. The average size is 

 much smaller, and the average color much darker. 2nd It 

 is perceptibly a less elongate species (f" g . 3rd. The head 

 is entirely black, as indeed is almost the case with variety 

 dubia of the preceding. 4th. The antennte are always basally 

 brown-black, though often dull rufous towards their tips, 

 the scape being always brown-black, which is never ihe 

 case in varians, even in the dark, variety dubia 5th The 

 entire thorax and abdomen are black, save that usually 

 there is a more or less extensive honey-yellow or rufous 

 spot on the side of the coUare, which in one autumnal g 

 extends over its anterior half above, and save that in one 

 vernal (^ the suture at the tip of the abdominal peduncle 

 is rufous, and in one autumnal g the lower part of the abdo- 

 men is piceous. 6th. The legs are on the average more 

 heavily marked with black, aud the coxa; are chiefly black. 

 7th. The dusky stigmatic patch is never widened behind the 

 black stigma, is of a, pale tint with its posterior boundary 

 less defluitely marked, and is occasionally reduced to a shovt 

 dusky cloud, reaching only half way or even one-third of 

 the way across the wing. Length ^ 0.05—0.10, g 0.07—0.10 

 inch. 



Described from 3 (j' 2 g, bred Sept. 22nd— 24th, from the 

 Cynipidous Oak-gall Q. Jicus, Fitch, of the same y.,ar's 

 gi-owth, and 40 j^ 16 g , bred May Sth— 20th, from the same 

 gall of the preceding year's growth. This species presents 

 some remarkable analogies with the variety dubia of the 

 preceding; .and the gall (i. ficus, in which it is parasitic, 

 grows on White Oak— a species belonging to the same group 

 of Oaks as the Burr Oak, on which the gall that produces 

 dubia occurs . 



GV 



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