198 A HISTOKY OF EECENT CRUSTACEA 



SO as to make a perfect orbit and to cover the ocular seg- 

 ment. It is said to liave the antennse of Palinurus, the 

 trunk-limbs like those of Scylla/rus, the carapace like that 

 of Astacus, and the pleopods like those oiScyllarus, so as to 

 form a truly inosculant genus. The type species is Synaxes 

 hybridica, Spence Bate, from the West Indies. Spence 

 Bate himself observes that ' Palinurellus, von Martens, ac- 

 cording to that author differs from Synaxes in having the 

 posterior pair of pereiopoda chelate in the female,' but does 

 not explain how that can be any distinction, if, in Synaxes, 

 * the pereiopoda are like those of Scyllarus,' as he declares 

 them to be, for in Snjlla/nis also the last pair are chelate 

 in the female. The student must be prepared sometimes 

 to find it as difficult to reconcile authors with themselves 

 as with one another. Under the circumstances one may 

 accept the decision of Dr. Boas, quoted with evident ap- 

 proval by von Martens, in 1882, that Synaxes is a synonym 

 of Palinurellus. 



The strange form known as Phyllosoma was at one time 

 regarded as belonging to a distinct genus, but is now 

 known to be larval, by such marks as the median eye, and 

 the rudimentary character or unjointed condition of the 

 various parts. A considerable number of specimens of 

 Phyllosoma were obtained by the Challenger, of sizes 

 varying from the seventeenth of an inch up to an inch and 

 two-fifths, the latter being larger than some specimens of 

 Palinurus that have attained the permanent form. In a 

 general way the Phyllosoma forms may be assigned to 

 different stages in the development of the Scyllaridae and 

 Palinuridse, bat to assign the successive stages to par- 

 ticular species does not seem always possible at present, and 

 in especial there appears to be an awkward gap between 

 the most advanced Phyllosoina and the earliest post-larval 

 form. No such perplexity, however, affects the first 

 larval form, or brephalos, when actually extracted from 

 the ovum. A specimen of this kind is shown on Plate IX., 

 in Spence Bate's figure of a juvenile Palinurus vulgaris. 



