POST-LARVAL STAGES OF JASUS LALANDII. 103 



muscles, destined to control the active movement o£ the exopodite in the next 

 stage, are specially marked. The endopodite is much coiled on itself, so 

 that it is not very much longer than the exopodite. Such coiling occurs at 

 the proximal end of the first segment, where the limb is completely bent on 

 itself, the remainder of its length being quite straight. The second segment 

 of the endopodite is relatively short and straight; the third is the most 

 coiled, there being one or two complete coils, gradually passing into mere 

 undulations, and eventually into the straight distal part of the segment. 

 The last segment is short and straight. The exopodite is not shortened by 

 such coilino- of the limb under the cuticle ; it is alreadv divided into 

 segments more or less distinctly', but there are no swimming setse. 



The second pereiopod (fig. 10) is very similar to the first. 



The third pereiopod (fig. 11) has the first two segments well developed and 

 somewhat similar to those of the preceding appendages; the second, however, 

 is rather slender, slightly coiled, and not marked off clearly from the suc- 

 ceeding. It also has the rudiment of an exopodite at its distal extremity. 

 The first segment of the endopodite is long, somewhat slender, and coiled at 

 its proximal extremity, the second is short and straight, but the third is long 

 and very much coiled at its proximal end for a little over half its length. 



Th-Q fourth pereiopod is represented by a slight swelling between the base 

 of the third and the commencement of the abdominal reo-ion. In Paliimrus 

 vulgaris the fourth and fifth pereiopods are present on hatching. 



Phyllosoma of 1-7 mm. [Fig. 12] PL 14. 



The stage succeeding the naupliosoma is the characteristic phyllosoma, 

 with transparent body, without the locomotory setae of the antennae, and 

 provided with locomotory setse on the exopodites of the walking-legs. The 

 spines and setse covered by cuticle in the last stages are now exposed, and 

 the appendages, which were formerly coiled up under the cuticle, now 

 become straight and about double their former leno-th. Though this 

 transformation is thus effected at a single ecdysis, there is no stage at which 

 the larva is not provided with active swimming organs, for, as was observed, 

 the cuticle with the swimming setse of the antennse is shed some time after 

 that of the other appendages, so that by the time these were lost those of the 

 exopodites of the pereiopods were in full activity. 



The body is now transparent, being devoid of yolk-granules, though some 

 may be seen in the intestine in the abdominal region. There are also 

 present the characteristic red pigment spots seen in the naupliosoma, and 

 present even in the embryo before hatching. 



On the under side of the body a number of closely-set small projections 

 were seen under the microscope. These cover the whole of the ventral side 

 of the thorax, from the third maxillipedes to the beginning of the abdominal 



