DR. BOAS ON THE SQUILLIDA 279 
CHAPTER XIX 
SUB-ORDER IV.—STOMATOPODA 
THE carapace is feebly developed, leaving uncovered at 
least the last three segments of the trunk; the pleon is 
powerful, and, hike the carapace, usually depressed, not 
laterally compressed. The eyes are stalked. The second 
antennee have a scale. The mandibles have a small or 
rudimentary ‘palp.’ The three pairs of maxillipeds and 
the two following pairs of appendages are variously modified 
as six-jointed prehensile limbs, with epipods, but without 
exopods ; the second maxillipeds being predominant in 
size andimportance. The three following pairs of legs are 
feebly developed, with exopods, but withoutepipods. The 
first five pairs of pleopods generally carry eacha pair of large 
ramified branchiez arising from the outer branch. There 
is a special apparatus on the inner branch of the first 
pleopods in the male. ‘The caudal fan is powerful. The 
heart is elongate, with several pairs of lateral venous fis- 
sures. ‘The ovaries and testes lie chiefly in the pleon, and 
have their two halves united by amedian piece. There are 
no spermatophores. The spermatozoa are simple, rounded 
cells. The young are hatched not as Naupli, but in a more 
advanced stage. ‘The carapace of the young ‘is largely 
expanded. 
The above definition is chiefly taken from that given 
by Dr. J. E. V. Boas for the ‘Order Squillacea,’ in his 
highly esteemed ‘ Studies on the Relationships of the Mala- 
costraca.’ It is in this sub-order that the typical number 
of twenty-one segments has been distinguished in a 
single animal. Usually the first antenne have three flagella, 
one of the two principal ones sending off a branch from 
