Mr. C. Spence Bate on two new Crustacea. 411 
rami unequal, the longer being about half the length of the 
basal joint. 
Length 4 inch. 
Lestrigonus spinidorsalis differs from any species of the genus 
that I have met within having the last two somites of the pereion 
and the first three of the pleon produced in the median line of 
_ the dorsal surface posteriorly to a sharp-pointed tooth or spine. 
It bears in all other respects some considerable resemblance to 
Lestrigonus exulans; and I was much inclined to think that 
the dorsal feature might have been the result of some more 
Fig. 2. 

Lestrigonus spinidorsalis, n. sp. a, second gnathopod. 
or less permanent injury; but close inspection, frequently 
repeated, has compelled me to believe that the spinous 
dorsal formation is characteristic of the animal, and one 
by which it may be readily distinguished from all other 
species. 
The eyes are large, the antenne subequally long and slender, 
about one half the length of the animal. The gnathopoda 
are short but not feeble; the first two pairs of pereiopoda are 
strong and robust; and the three posterior pairs are long and 
slender, having the propodos long with the anterior and pos- 
terior margins parallel. 
Length ? inch. 
