Vor. II, Pt. 11] HEBARD—DERMAPTERA AND ORTHOPTERA 325 
literosa (Walker ), that the student might easily imagine he had 
a hybrid before him. The present large series from Abingdon 
and Duncan islands shows, however, that this is the dominant 
type on those islands, typical melanocera, however, occurring 
also on Duncan Island. Snodgrass also reports intermedia as 
the only form found on Bindloe Island, while a specimen from 
Jervis Island is now before us. 
We do not agree with Snodgrass in considering this species 
absolutely intermediate between melanocera and literosa, for the 
larger series now at hand show a distinctly closer affinity to the 
former species. Individual variability is, however, consider- 
able, and is largely due to the varying degrees of weak infusion 
of the striking colors and color-pattern developed in melanocera. 
As the insect here considered represents a type distributed 
over several islands, and represents a condition combining the 
features of two distinct types of the same genus found on the 
same or adjacent islands, the problem as to the proper name 
designation is most difficult. 
Three theories are advanced. 1. The ancestral stock is in- 
termedia, and from it have developed two species, melanocera 
and literosa. 2. That melanocera and literosa, having at some 
time become isolated on one of the islands, interbred and the 
hybrids, through generations, developed into the species iter- 
media. 3. That melanocera, intermedia and literosa are de- 
scendants from a common ancestor, which became isolated on 
the various islands of the Galapagos Archipelago and divided 
into the three species now extant, the ancestral type having dis- 
appeared. 
We prefer the third hypothesis, though we must admit that 
the problem is far from being solved®. Very similarly puzzling 
differences are found in some of the birds of the Galapagos. 
The species is fully discussed by Snodgrass, the present ma- 
terial showing nothing of additional importance. We do not 
find literosa sufficiently close to intermedia to warrant consider- 
ing the Hood Island race of that species (/. punctata), in- 
termediate between the Chatham Island race of that species (J. 
literosa) and the present species, as stated by that author. 
8 Snodgrass offers another hypothesis, i. e., that intermedia is a form of melanocera 
varying toward literosa, or the opposite. That author prefers the hybridization theory 
and ae not consider the third theory offered here as the probable solution of the 
problem. 
