Vv STOMATOPODA—LARVAL HISTORY 143 
with the thoracic appendages developed as biramous organs as far 
as the fifth pair, and with a single abdominal pair of limbs. 
The abdominal series of limbs is next completed; the second 
thoracic limb assumes its 
adult raptorial structure, 
but the succeeding three 
limbs become greatly re- 
duced and may entirely 
degenerate, leaving the age EKA We ; 
‘ : . Fra. 99.—Erichthoidina larva of a Stomatopod, with 
posterlor six thoracic five pairs of maxillipedes, and the first pair of 
segments without limbs. eae eae x 10. (From Balfour, 
Usually the anterior . 
three pairs are only reduced, and then redevelop side by side 
with the small posterior limbs as they appear. This larva is 
then termed the “ Erichthus” (Fig. 100); but when they com- 
Fig. 100.—Older Erichthus larva, with six pairs of abdominal appendages, x 15. 
(From Balfour, after Claus. ) 
pletely disappear the larva is called a “ Pseudozoaea,” owing to 
its resemblance to the Zoaea stage of the Decapoda, which is 
also characterised by the suppressed development of the thoracic 
segments. 
The so-called “ Alima” larva of Sguilla is also a Pseudozoaea, 
but it is apparently arrived at directly without the previous 
formation and degeneration of the anterior thoracic limbs, the 
larva hatching out from the egg in the Pseudozoaeal stage. 
Fam. Squillidae—Of the six known genera none extend 
into the cold subarctic seas; the majority are characteristic of 
the warm or tropical seas (Gonodactylus), some of the species 
having very wide ranges, e.g. @. chiragra, which is completely 
circumtropical, and appears to have entered the Mediterranean at 
some period, though it is very rare there. 
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