148 DEVELOPMENT OF PALTNURUS VULGARIS. 



cephalon, and destitute of even tlie rudiment of an exopodite. The 

 fourth and fifth pereiopoda are not yet developed, but represented 

 by two minute rounded buds on either side of the root of the abdo- 

 men. The abdomen is without developed appendages, but the 

 sixth pair of pleopods is indicated already by a slight rounded out- 

 growth on each side of the telson. The termination of the telson 

 is truncated, without the slightest trace of bifurcation (PI. VIII). 



Among the Phyllosomes I obtained from the sea there are all 

 sizes and stages, from the newly-hatched stage just described, up to 

 one 7 mm. long, which is the largest and most developed I have 

 yet obtained. The developments that have taken place at this 

 stage are as follows : — The second antenna is now a little, but not 

 much longer than the first. Two basal joints have been differentiated 

 in the first antenna, and from the end of the second has grown out 

 a simple process, the commencement of the internal filament. One 

 nodal division is also visible in the basal portion of the second 

 antenna. The exopodite has began to sprout out from the second 

 joint of the second maxilliped, but the rudimentaiy stump of the 

 first maxilliped, and the rest of the oral appendages, are quite un- 

 changed. The exopodite of the third pereiopod is fully developed, 

 and the fourth and fifth pairs of pereiopoda have developed con- 

 siderably, the fourth being biramous and almost as long as the 

 abdomen, the fifth still simple and somewhat shorter. The pleopods 

 of the abdomen are considerably developed. The sixth pair or 

 swimmerets are of some length and distinctly biramous, while the 

 four preceding pairs are also visible, and each commencing to divide 

 into exopodite and endopodite. No appendage is developed at all 

 on the first abdominal segment. The cephalic shield which, in the 

 newly-hatched stage, covered only the second maxilliped, leaving all 

 the rest of the thorax with its appendages free, now extends back 

 so as to cover the origin and base of the third maxilliped (PI. IX). 



There can be no doubt at all that the Phyllosomes I have obtained 

 belong to Palinurus vulgaris ; Dohrn's and Richters' investigations 

 have shown clearly that the larvae of 8cyllarus can be distinguished 

 from those of Palinurus at all stages, and Scyllarus ardus {Arctus 

 ursus) is the only other species of the family which occurs near 

 Plymouth, and this form is very rare. It becomes possible, there- 

 fore, to identify the Phyllosoma larvae of Palinurus vulgaris if they 

 have been sufficiently described or figured in previous literature. 

 It is not possible to identify satisfactorily the forms described by 

 Milne Edwards and Richters ; they come from distant coasts, such 

 as those of Africa, Asia, and New Guinea. However, it may be 

 mentioned that Richters is very possibly wrong in stating that the 

 first maxilliped was wanting in his youngest Palinurine form, 7 mm. 



