1913. ] S. Kemp: Crustacea Stomatopoda of the Indo-Pacific Region. 9 
allied forms belonging to the ovatoria section of the genus Squilla, the precise size of 
the cornea is of great importance ; but inasmuch as its breadth becomes proportion- 
ately less as the animal increases in size, the character must be used with caution. 
The number of times in which the breadth of the cornea is contained in the median 
length of the carapace affords a ready means of comparing the size of the eye in 
allied species, and the figure so obtained I have designated the ‘‘ corneal index.’’ 
The mandibular palp, by the number of segments which compose it and by its 
presence or absence, affords useful taxonomic indications; but there is reason to 
believe that the importance of the character is by no means equal in the different 
genera.' In Squilla, for instance, its value is purely specific, in Gonodactylus it is of 
considerable assistance in breaking the genus into groups, while in the case of Pseudo- 
squilla stylifera it seems likely that geographical races can be separated by its means. 
The mandibular palp may easily be examined without dissection by deflecting one of 
the great raptorial claws. The palp will then be seen directed forwards and lying 
close up against the side-wall of the carapace (text-fig. 5, p. 12). 
The precise relations which the six segments that compose the thoracic limbs of 
the Stomatopoda bear with the seven (or eight) recognized in other Malacostraca are 
as yet unknown. I have used the familiar terms ischium, merus, carpus, propodus 
and dactylus purely for the sake of convenience: it must not be thought that by 
such application any homology with the Decapod limb is intended. 
In descriptions of species of Squil/a it has been found convenient to note the 
presence or absence of the terminal spines on the abdominal carinae in tabular form. 
Squilla nepa, for instance, has the following spine-formula :— 
Carinae. Abdominal somites. 
Submedian 5c oe : a 4, 5, 6. 
Intermediate .. se oe 56 A) Sty clk iq (Oe 
Lateral ye ac fe 6. (OD) Sine aay, 
Marginal an Be at : dtm #45 Sep 
By this it is to be understood that the submedian carinae of the last three 
somites terminate in spines. The intermediate carinae of the last four somites and 
the lateral carinae of the last five also have a spinous ending, while, in addition, 
the intermediate carinae of the second somite and the lateral carinae of the first 
somite (figures enclosed in brackets) end in spines in some, but not in all, of the 
specimens examined. All the marginal carinae are produced as spines: the marginal 
carina of the last somite does not exist in any species of Stomatopod and the spine 
which is found at the postero-lateral angle of that somite is a continuation. of the 
lateral carina: 
Brooks considered that the form of the processes on the endopodite of the first 
abdominal appendage of the male would be found to yield much assistance in the 
taxonomic treatment of the group. In my experience, however, this is not the case 
and I have consequently omitted reference to this appendage in the systematic 
account of the species. (Cont. on p. 14.) 
' Further reference will be found under the separate generic headings. 
