igi3-] S. Kemp : Crustacea Stomatopoda of the Indo-Pacific Region. 9 



allied forms belonging to the oratoria 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 th? 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. 1 In Squilla, for instanc';, 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 sty lifer a 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 Squilla 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 .. .. .. .. 4,5,6. 



Intermediate ... .. .. .. (2), 3, 4, 5, 6. 



Lateral .. .. .. . . (1), 2, 3, 4, 5, 



Marginal .. .. .. . . 1, 2, 3, 4, 5. 



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 1 have consequently omitted reference to this appendage in the systematic 

 account 1 of the species. {Cont. on p. 14.) 



1 Further reference will be found under the separate generic headings. 



