MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES. 15& 



Larva. 



(PI. X.\. iig-s. 1-7.) 



Stretch, 111. Zyg. and Bomb. N. Aiuer., i, ji, il(l, jil. 10. lig. 'J, 1872. 



Lintmr, Eut. t'ontr., iv, p. 7G, 1878. 



Tc-pper, Bull. Brooklyn Ent. Soc, i, p. S, 1878. 



Goodhue, Can. Ent., xiv, p. 73, 1882. 



Packard, Fifth Rep. U. S. Ent. Comin., lus. liij. Forest Tree.s, p. 15.'), 18110. (Fig.) 



Proc. Bost. Soc. Nat. Hist., xxiv, pp. .".22-.".23, 18'J0. (8tugc III-V.) 



JoLirn. N. York. Ent. Soc, i, pp. (53-68, 18il3. 

 Dijar, PsycLe, vi, pp. 191-19(i, Dec. 1891. 



Psyche, vi, pp. 351-.353, Nov.. 1892. (Description m Cull of egg :in(l of the five larval stages of var. 



IKirttainlia.) 



Moth. — Thorax aiul head cinereotis; the tuft ou the patagia or shoulder tippet.s tiitped with 

 dark browu. Fore -nings rouuded and .somewhat produced toward the apex; of a delicate frosty 

 white aud brown. Along the ends of the subcostal venules of the fore wings are long streaks of 

 brown; in the apical and subapieal spaces are two long, longitudinal, broad streaks, oblique and 

 parallel to the co.sta, which termiDate just below the apex; middle of the wing wliite. A long, 

 broad line extends from the base to Just above the inner angle on the outer margin, liued below 

 with white, and dcdected upward along the outer edge. Tuft ciuereous. lieueath, cinereous, 

 costa darker. The female darker than the male. Hind wings white, the region of the internal 

 angle and tuft dark brown. Legs and abdomen cinereous. 



Four examples from Colorado are slightly darker and less fulvous than in Wisconsin aud New 

 England individuals. 



A $ '] from Franconia, N. H.. received from Mrs. Slosson, is very large, expanding CO mm. 

 It has more dark browu ou the fore wings than usual, a large costo ai>ical dark brown i)atch 

 coutaining a white slash and a large wide brown region ou the internal edge, extending up the 

 outer edge to near the apex, the ends of the independent and cubital venules white; but it is not 

 nearly so dark in the middle of the wing as in \ar. iwrtlandia. 



The imago of Stretch's caU/oriiica does not seem to diiier from the Eastern form, and by Messrs. 

 Lintner and Dyar it is regarded as cospecilic with the Eastern form. In respect to P. jwrtlanflia, 

 I also regard this as only a climatic, melanotic variety of the Californian aud Eastern dimidiata. 

 I am indebted to Mr. Dyar for a specimen, though it is somewhat rubbed. 



The Oregon form is much darker and slightly larger than the Ea.steru form, and thus 

 conforms to the law in geograjihical distribution which obtains in the Geometrids, that ou the 

 Pacific Coast, where the climate is humid, there is a tendency to greater size and darker, almost 

 melanistic cohn'ation. Var. iwrtlaudia is a melanotic form, aud is dark mouse or sable-browu. 

 The fore wings are marked precisely as in the normal forms, but the browu marks and slashes are 

 blacker, and the ground color of the wings smoky or dusky, not being frosted with white scales. 

 Hind wings dark mouse color ou the inner edge, forming a broad band, extending to the heavy 

 dark patch at the inner angle, while the rest of the wing is sordid or smoky white, not frosty 

 white. While the length of the fore wing of my type from Maine is 25 mm., that of portlundia 

 is 21) mm., tlie entire expanse being ')i mm. 



I find that the venation of portlandia does not differ from that of the Eastern dimidiata. 



Mr. Lintner gives at length his reasons for regarding our dimidiata [rimosa) as cospecific with 

 the European dictwa. Sj)ecimeus were sent by Mr. von Meske to Dr. Speyer, who did not doubt 

 that the two species were identical, the difference being very slight. lie also gives at length the 

 re.sults of his own coinxjari.sons. He likewise refers to the fact, which I have verified, that there 

 are two forms of the larva, both iu Europe and in the United States, both on the Atlantic and 

 I'aciflc coasts, oue being without aud the other with a j'ellow lateral stripe. I should not hesitate 

 to regard the species as common both to Europe and America, were it not that the European 

 species is without a horn. 



In the figures of the British larva of dictwa in Buckler's work, published by the Kay vSociety, 

 {his fig. lb, PI. XXXV) the stripe is present ou the eigiith abdondnal segment, while the large horn 

 of our form is represented by only a hump. In oue of Buckler's figures the humj) of the greeu 



