372 



to our series. We have the species in good series from intermediate 

 localities, including specimens reared by Dr. McDunnough at Decatur. 



The Murtfeldt collection, now at Cornell University, contained 

 three specimens labelled as types of this species, which were submitted 

 to us for examination. All bore the same rearing number and the 

 locality Mo. One proved to be a specimen of Marasmarcha pumilio 

 Zell., the others corresponded to our idea of anibrosiac. We labelled 

 a S lectotype and the other, a 9 , which is in the Barnes collection 

 through the kindness of Dr. J. C. Bradley, may be regarded as a para- 

 type. One specimen in the Fernald collection bore type and breeding 

 labels in Miss Murtfeldts handwriting, and we have therefore labelletl 

 it as a paratype. 



We have not been able to examine the types of pcxplcxus Gross- 

 beck, but placed it as a synonym of ambrosiae by means of the descrip- 

 tion. A comparison of specimens with the type, which Mr. Frank E. 

 Watson has very kindly made, confirms this opinion. 



Ambrosiae is an extremely variable species in most details of color 

 and pattern, and can be confused rather readily with some species of 

 Oidaematophoriis in a casual examination. The stalked radial branches, 

 however, place it with a group of species from which it is readily 

 separable. The single dorsal dots on the abdomen distinguish it from 

 iiiquiiiatns, of which it has so long been regarded as a synonym. In 

 inquinatus the dorsal dots are paired. 



Miss Murtfeldt reared the species before describing it, and in 

 her original paper gives the following account of larva and pupa : 



"Larva: Length 0.35; diameter, 0.09. Form depressed. Color pale greenish 

 gray, with ver\' characteristic dark markings and lateral tufts of long, white, 

 silken hairs. Head small, light brown, corneous, retractile. Segment 1 with 

 a dilated, partially free, shield-like collar covering top and projecting over the 

 head. The ornamentation of this collar consists of five central minute brown 

 dots, with four still smaller black ones on each side, from each of which pro- 

 ceeds a short, curved bristle. The projecting edges are fringed with soft, light 

 hairs. Segments 2 and 3, gradually broadening backward, ornamented on dorsum 

 with two oblong, pale-brown spots on either side of a triangle of very minute 

 black dots, and having a larger black dot on each outer side. Two short bristles 

 arise from each of the more conspicuous spots. Abdominal segments, each with 

 four, somewhat elevated, brown spots, from which proceed single, short, back- 

 ward-curving bristles. Between the posterior pair of brown spots are two smaller 

 black ones, each of which forms the base of a very short clubbed piliferous 

 process, which turns backward, resting flat upon the surface. 



