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eluded that fulvicollis is a Philonix while erinacei is an 
Acraspis. My recent studies in the U. S, National Museum 
lead me to agree with Weld’s interpretation. At the same 
time, direct comparison of the holotype and paratypes of 
fulvicollis and nigricollis , of paratypes of gillettei, and of the 
holotype of Gillette’s niger leads me to conclude that all these 
names are synonyms. Each holotype is different from any of 
the others, but every variation covered by the types, and many 
additional variations are included in every extensive series we 
have represented in our collections. 
What we appear to have here is a highly variable complex 
that grades into variety canadensis to the north and variety 
major to the south. In the intermediate territory, which is 
much of the northeastern quarter of the United States, one 
finds canadensis and true major and every conceivable inter- 
grade between the two. The intermediate types are every- 
where the most abundant. As one goes north, true canadensis 
or hybrid individuals appearing to have a great deal of cana- 
densis blood are predominant. Toward the south, major simi- 
larly asserts itself. 
One examining several thousand insects of this remarkable 
complex cannot doubt its hybrid origin from canadensis x 
major. The chief question to be raised is whether we are 
warranted in calling such a heterogeneous population a spe- 
cies. It is much like Cynips pezomachoides erinacei which 
also seems hybrid in origin, and the same geologic history that 
explains (p. 398) the origin of erinacei should fit fulvicollis . 
The two occur in the same area. In both cases the northern 
variety probably met its opportunity to hybridize with the 
southern variety upon the advance of the Pleistocene glaciers, 
and the retreat of the glaciers offered an extensive territory 
for the isolation and development of the hybrid. Fulvicollis 
is not as thoroly fused as erinacei. Nevertheless, the wide- 
spread distribution of the complex may warrant its recognition 
as a distinct taxonomic unit, whatever we may choose to call it. 
The individuals which are the types of nigricollis , niger, 
and gillettei are only larger or smaller, lighter or darker, more 
hairy or less hairy representatives of this fidvicollis complex, 
and not nearly as diverse forms as a larger series of true 
fulvicollis will show. 
Cresson’s list of the Bassett types in the Philadelphia 
Academy states that gillettei came from Fort Collins, Colorado. 
