122 



Twenty- SIXTH Report on the State Museum. 



Fig. 4. 



The larva of Alypia octomacidata is marked on each segment with 

 eight black bands (counting the two which border the broad central 

 ^i<^ 3- orange band), as shown in a of Fig. 3, 



and more distinctly in the enlarged 

 view of one of the segments at h ; from 

 the black dots long white hairs are given 

 out (represented too short in the figure), 

 and below the stigmata, on segments 

 four to nine, is a row of white spots, 

 with a large white spot extending over 

 the incisure of the tenth and eleventh 

 segments. At c, a view is given of the 

 imago of this species. 



The larvae of Eudryas grata and of E. unio have six black bands 



and a central orange one on each of the 

 principal segments; they are without 

 the white lateral patches, and have a 

 prominent hump on the eleventh seg- 

 ment. A representation of the imago 

 of E. grata is given in Fig. 4, for com- 

 parison with octomaculata and ejpimenis^ 

 and to illustrate the fact well known to those who have studied the 

 larvae of our Lepidoptera, that very dissimilar moths are frequently 

 produced from larvae closely resembling one another.* 



I regret my inability to give, at the present, the differential fea- 

 tures of grata and unio. At maturity they differ in size, unio being 

 invariably the smaller. In markings they resemble one another so 

 closely, that Mr. Riley, after a critical comparison of examples of 

 unio which I had sent to him, with some examples of grata in his 

 possession (probably alcoholic), writes me, that he finds the two spe- 

 cies absolutely indistinguishable. 



While specific differences may not be detected in alcoholic indi- 

 viduals, there is scarcely any doubt but that sufficient characters for 

 their identification could be obtained from a comparison of the colors 

 of the living forms. Having lately seen a large number of grata 

 larvae (at Portland, Me., in August, 1873), I may safely assert that 

 the two species differ materially in their general aspect. While 

 unable to state from recollection what these differentia are, I believe 

 that unio will prove to be characterized by more prominently marked 



* The figures illustrating this article are from the excellent drawings of Mr. C. V. 

 Riley. 



