IG PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
developed {as. I, as. II, etc.). These are called the first, second, 
third, etc., counting from front to rear. 
The ventral edges of the nota do not meet and between them lie 
the corresponding sterna or ventral plates (Bauchplatten, Bottcher; 
plaques ventrales, Pandelle). These are subquadrate. Their num- 
bers are the same as those of the segments to which they belong. 
Anterior to the ventral plate of the second segment lies a similar 
but smaller sclerite, representing that of the vestigial first segment. 
Its notum remains as two narrow, ridge-like plates (PI. 5, fig. 30) 
approximated to the anterior edge of the second notum, one on each 
side of the ventral plate. 
Each segment has two spiracles (PI. 5, fig. 30, sp.) on the ventral 
surface of the notum, one on each side. Those of the vestigial first 
segment are indistinct and occur on the remnants of the notum as 
above noted. 
The ventral plate (P4. 5, fig. 30, vp.i; PI. 6, fig. 37, vp. IV) which 
lies between the ventral edges of the fifth notum, I consider to belong 
to the fifth segment. Pandelle refers to it as the sixth plate (sixieme 
plaque); Bottcher follows his example but in his systematic work 
designates it as the fifth segment (fiinftes Segment). This seems not 
only unnatural but also anatomically incorrect. The plate is highly 
modified in connection with the copulatory apparatus. Further 
discussion on this point belongs under the consideration of the genital 
segments. 
The second ventral plate shows a slight indentation in the middle 
of its anterior margin. In this indentation is a small hook-like process. 
No reference to it has been found and its significance is unknowni. 
Vestiture. — Dorsally the abdomen is covered with short, somewhat 
decumbent bristles. Ventrally the vestiture is more hair-like and 
erect. The ventral plates are distinctly hairy. The hairs of the first 
plate are long, those of the second and third successively shorter. 
The hairiness is erect and evenly distributed on the fourth plate 
(anatomical). 
Genital Segments. 
In the following discussion the genital segments (PI. 5, figs. 30, 31; 
PI. 6, figs. 37, 40) are considered to be pulled from their normal posi- 
tion within the end of the abdomen and extended backward and up- 
ward till the relation of their parts is similar to that of the segments of 
