214 THE HUMBLE-BEE vill 
4, PSITHYRUS BARBUTELLUS, Kirby. 
QUEEN.—Of medium size; length 17-I9 mm., ex- 
panse 36-39 mm.; sometimes smaller. 
Head black, with some dull yellow hairs on top. Thorax 
black, with a dull yellow band in front and a narrow one 
behind. Abdomen black, with sometimes some dull yellow 
on the Ist segment, and with the 4th and 5th segments, 
sometimes also the edge of the 3rd segment, white. 
The 6th dorsal segment has a dull shine, is punctured, 
and bears a faint raised line down its centre. 
The elevations on the 6th ventral segment form a trans- 
verse, crescent-shaped mark, which does not nearly reach to 
the apex of the segment, and has a narrow division in the 
middle ; between the crescent and the apex the segment 
is clothed with short velvety golden-brown hairs. The 
crescent-shaped elevation affords an easy means of dis- 
tinguishing this species from all others. 
MALE.—Length 15-163 mm., expanse 29-32 mm. 
Head black, with some yellow hairs on top. Thorax 
black, with a yellow band in front and a narrow yellow band 
behind. Abdomen black, with the 1st segment more or less 
yellow ; the 4th and 5th segments white ; the 6th white at the 
sides, black in the middle; 7th more or less black. The 
white often extends on to the 3rd segment. 
The coloration is therefore very like that of Ps. dzs- 
tinctus, except that there is no definite tinge of yellow on 
the sides of the 3rd segment ; in very fresh specimens, how- 
ever, the white area is sometimes faintly tinged at its base 
with yellow, but this soon fades away. 
Coat uneven—rather shorter than in adzstznctus ; the 
hairs slightly stiffer, slightly coarser, and slightly less 
dense than in dzstznctus. 
On the 6th ventral segment, near the apex, there is a slight 
mound on either side of the middle: 
Hind metatarsi more slender and longer than in azs- 
