1884] 
of the same segment project two supra-anal, conical, fleshy, res- 
iratory tubercles, one-fourth the length of the entire segment, 
which separate and close together at the will of the animal. 
These two tubercles (4) give rise to two main longitudinal tracheæ 
which extend to the head; they end in a tuft of fine sete. 
i 
Entomology. ee 
c 
Fic. 2,—Bdella marina Pack. 
When extended the prothoracic segment is considerably pi 
others. The head is one-third as large as the proth 
b 
