Genus Mucidus. 133 
and bear thick spines apically and a lateral inward tuft; there 
is also a prominent tuft of chaetae near their base (c). The 
mandibles (fig. 72, e) are serrated and powerful, having one large 
and three smaller teeth and two accessory pieces (f and g).. The 
thorax is smaller than the head, and has six median anterior 
chaetae in two groups and six lateral (three on each side) in line 
with the median ones, but further apart ; on the sides are two 
pairs of prominent projections, each provided with long chaetae. 

Fig. 74. 
Mucidus alternans. Westwood. 
Pupa : a, Respiratory siphon ; b, 
first abdominal segment. - 

Fig. 73. 
Mucidus alternans. Westwood. 
I. Head of young larva: a, antennae ; b, character- 
istic frontal projections ; c, lateral tufts. II. 
Respiratory siphon of larva. 
The abdomen has also paired bristles; the siphon is long and 
thick, ending in two (?) flaps; on its lower side are rows of small 
bristles in pairs. 
_The pupa, with curious short and broad trumpets (fig. 74, a). 
No caudal fins; on the first abdominal segment a single bristle 
in front and a large plumose one behind (fig. 74, b). 
The larvae are preyed upon by Megarhinus, one specimen 
sent me of the latter having eaten all the Mucidus, except the 
head, which was sticking out of its mouth. 
