PARKER: NEW ENGLAND SARCOPHAGI DAE, 37 
somewhat l)iit tlic differences are obscure. Color seems to \)v their 
most useful character and is quite constant, hut is of more interest in 
other genera than those imder discussion. The comparati\e length 
of the second and the third segments is sometimes helpful in separating 
species but is hardly to be relied upon. It is sometimes indicative 
of species groups. The outline of the third segment is usually linear, 
but it may be broadened distally; color is, as a rule, imimportaiit. 
The arista (PI. 2, figs. 9a, 9b) may be plumose with long or short hairs 
(shortly phniiose of descriptions) or pubescent (Wohlfartia, etc.). 
The plumosity is generally confined to the basal half or thereal)outs, 
but in one undescribed species of Sarcophaga extends nearly to the tip. 
Walker described a species, S. virgil, stating that the arista had but 
two segments; I have never found more or less than three. The base 
of the third segment is always slightly enlarged ; at the outer end of 
this enlargement and slightly beyond, the chitin is often less deeply 
pigmented than that of the remainder of the arista forming a light- 
colored band. While this is present in some species and absent in 
others it is too variable to be of value. 
The palpi offer but two characters: shape and color. The former 
is of little value because of marked variations, the latter is generally 
dark but in some species such as Sarcophaga fuhipes Macquart it is 
distinctly dull orange or fuhous, while in one, as yet undescribed, the 
tendency is to be slightly hyaline. 
Thorax. — The most important and useful characters of the thorax 
are found on the legs and in the chaetotaxy. Dorsally it is traversed 
longitudinally by five dark-colored stripes (vittae). The median and 
first lateral pair extend from the anterior end of the prescutum back 
to the scutellum and are usually well defined. All three may be of 
equal width or the median the narrowest. The second lateral pair are 
blotchy and extend from the humerus back to the postalar callus. 
Between these dark stripes are others of lighter color. Paralleling 
the median stripe on each side and nearer to it than to the first lateral 
pair is a very narrow stripe differentiated from the remainder of the 
area in which it lies by its darker color. Along each side extends a 
line of small bristles or hairs depending on the nature of the vestiture 
of the metanotum. These stripes may end at the transverse suture 
or pass back a short distance beyond it. Ordinarily they are more 
distinct if the specimen is tipped forward so that the line of sight 
is nearly parallel to the dorsal surface. In the assidua group 
(Sarcophaga) they are rather indistinct. 
