LORICATA. 



279 



of a square plate. IMost of the limbs are still of a somewhat 

 embryonic stamp, but it should be mentioned that the three anterior 

 pairs of limbs of the thoraco-abdomen (second and third maxilli- 

 pedes and first ambulatory limbs) consist of uniramose rudiments, 

 while the two following pairs (second and third ambulatory limbs) 

 are still simple bud-like outgrowths. 



At a somewhat later stage, the second antennae, which are very 

 little shorter than the first, 

 show the rudiments of the 

 antennal glands at their 

 bases. The mandible, in 

 which the palp is wanting, 

 is slightly bilobate at the 

 tip ; the first maxilla is 

 bilobate, and the second 

 has incisions on its inner 

 edge which break it up 

 into three lobes. The first 

 maxillipede also, which was 

 simply truncated at an 

 earlier stage, is now a 

 short bilobed rudiment. 

 On the other hand, the 

 exopodites of the second 

 and third maxillipedes have 

 become reduced, while the 

 second and third ambula- 

 tory limbs appear distinctly 

 biramose. Further back 

 are found the small trun- 

 cated rudiments of the 

 fourth and fifth ambulatory 

 limbs. 



A similar condition of the limbs is found in the Palinums embryos at later 

 stages (Fig. 128). The first antenna («') is simple and unjointed, while 

 the somewhat longer second antenna («") shows the rudiment of a lateral 

 branch. The first maxilla (mx) is trilobate, the second bilobate. In the 

 two anterior maxillipedes {nif, mf") as well as in the third ambulatory limb 

 (i'"), the exopodite is vestigial ; the third maxillipede {mf"), on the contrary, 

 and the first and second ambulatory limbs {f, t") are provided with large 

 exopodites. The posterior region of the body contains the segments carrying 

 the fourth and fifth pairs of ambulatory limbs {t^, fi), as well as the abdominal 

 segments [1-6), and ends in a cleft telson. 



Fig. 12S. — An embryo of Palinitnis quadriconiis 

 with thoraco-abdomen turned back (after Claus). 

 a, anus ; a', first antenna ; a", second antenna ; 

 md, mandible; ml', mf", mf", first, second, and 

 third maxillipedes ; mx', mx", first and second 

 maxillae ; oc, Nauplins eye ; ol, upper lip ; ji, parag- 

 natha ; t', t", t"', first three amlmlatory limbs ; 

 t-*, fi, segments carrying the fourth and fifth ambu- 

 latory limbs ; x-x, bonndary of the cephalo-thorax ; 

 1-0, first six abdominal segments. 



