226 PALAEMON (EUPALAEMON) LENZII. 
22!/, mm. and 15 mm. long, while the straight distance 
between the Ist rostral tooth and the tip of the rostrum 
is just as long as the distance between this tooth and the 
posterior margin of the carapace. In the three other, younger, 
specimens the 1st rostral tooth is a little farther remote 
from the tip of the rostrum than from the hinder edge 
of the carapace. While in these younger specimens the 
rostrum attains the obtuse tips of the scaphocerites, it 
extends in the largest male to midway between these tips 
and those of the lateral terminal spines. As in Pal. duz 
the upper margin of the rostrum curves downward, while 
the tip projects either horizontally forward or appears very 
slightly turned upward; just as in this species no teeth 
of the upper margin prove to be situated in a higher 
level than the 1st rostral tooth, when the upper border 
of the carapace is placed horizontally. Different from Pal. 
dux, the rostrum appears less high, the distance between 
the lateral crest and the upper margin being much 
higher in that species than in Pal. Lenzii. In the largest 
a 
specimen the rostral formula is ae The upper margin 
is armed with 9 teeth, 2 of which are on the cara- 
pace, while the 3d is situated immediately before the 
orbital margin; the 2nd tooth is almost one and a half 
as far remote from the 1st as from the Srd, the 3rd to the 
7th are equidistant, the distance between the 7th and the 
8th is a little larger than the distances between the 3rd to 
the 7th; the foremost or apical tooth finally, is situated 
close to the tip, its distance from the penultimate tooth 
being one-third longer than the distance between the 
7th tooth and the 8th and 4-times as long as its distance 
from the tip. The lower margin is armed with 4 rather 
prominent teeth, the Ist situated just below the 7th of 
the upper margin, the 4th just midway between the apical 
tooth and the penultimate. The rostrum arises immediately 
before the middle of the carapace: the distance (3'/, mm.) 
between the tip of the 1st tooth, measured at the level 
Notes from the Leyden Museum, Vol. XX XIII. 
