338 Merrill—Structure and Affinities of Bunops Scutifrons. 
longation. In both these genera the posterior (dorsal) part of the 
post-abdomen is enlarged into a semicircular structure, which 
is flattened to a sharp edge and toothed. This form is widely 
different from that shown by Drepanothrix , Acantholeberis and 
Macrothrix , while that of Lathonura is wholly peculiar to itself. 
APPENDAGES.-ANTENNULES. 
The antennules of the Macrothricidce show three characters 
tic forms: 
Flattened and expanded at f M. laticornis. 
tip.-j Drepanothrix. 
L Acantholeberis. 
Flattened and twisted. 
Streblocerus. 
ANTENNULES, -J 
Ilyocryptus. 
Lathonura. 
M. rosea. 
Cylindrical.-j Opliryoxus. 
Grimaldina. 
Guernella. 
Bunops. 
Lateral sense-hairs are present as follows: 
None in female, -j Ilyocryptus , Drepanothrix. 
Lateral 
sense- 
hairs. 
C Opliryoxus. 
Proximal only. -j Macrothrix. 
(_ Acantholeberis. 
Distal only. . .. Streblocerus. 
1 proximal and 1 distal. .. -j Lathonura. 
Both. . •< 
C Grimcddina. 
1 proximal and 2 distal. .. •< Guernella. 
(_ Bunops. 
The antennules of Bunops are closest in general form to 
those of Lathonura , but are longer and more slender, and have 
two pairs of distal sense-hairs, while Lathonura has only one 
pair. In Grimaldina and Guernella the distal sense-hairs are 
