REPORT ON THE CRUSTACEA MA CRURA. 95 



pereion which is considerably more extended than in the preceding specimens, and leaves 

 the pleon embayed in a fork of considerable depth. 



The eyes are supported on long, slender, bi-articulate ophthalmopoda. The first pair 

 of antennae has the peduncle tri-articulate and supports two flagella, of which the 

 larger is furnished with a number of membranous cilia, which I believe to be auditory in 

 their function ; the smaller is slender and in an incipient condition : the second pair of 

 antennae is short, tapering, and multi-articulate; at its base, situated within the margin 

 of the carapace, is the foramen of the future phymacerite, and leading up to it the cellular 

 substance of the green gland, whose walls appear more delicate than those of the preced- 

 ing species : the oral apparatus is hard and firm, and the long, slender calcified tendon 

 of the mandible is threadlike and extremely delicate : the first pair of siagnopoda is two- 

 branched, curved and armed with several strong spines, some of which are fringed with 

 minute pointed processes, and the whole apparatus is in close contact with the anterior 

 extremity of the pereion, the anterior angle of which supports a small two-jointed appen- 

 dage similar to that which we found at earlier stages in the other specimen ; on the outer 

 side, also, there exists a small rudimentary process which is not seen in either of our 

 other specimens, and which Milne-Edwards figures 1 as being the incipient stage of " les 

 machoires de la deuxieme paire et la premiere paire de pattes-machoires " ; the next as 

 well as the five succeeding pairs, appears to be in a similar condition to those of the pre- 

 ceding example, but the seventh or ultimate pair is considerably longer and quite ecraals 

 in size the largest of the preceding, a circumstance that is more dependent upon specific 

 than upon developmental differences, since the specimens of other species which are larger 

 in size have their posterior pair in a much more immature condition. 



Again, in this present specimen the pleon is in a very immature condition, none of 

 the pleopoda being beyond the early budding stage except the posterior pair, and that 

 but slightly advanced. 



Development of the Scyllaeice. 



The foregoing paragraphs contain an account of the development of the Palinuridae, 

 so far as the specimens in the present collection enable me to trace it ; but some others 

 in my possession, which were obtained on the coast of Coromandel, by Sir Walter Elliot, 

 still further illustrate the. progressive changes in the genera of the Scyllaridas. 



The specimens appear to me to be identical with that described by Desmarest under 

 the name of " Phyllosome larges-cornes," and by Leach as Phyllosoma laticorne, but 

 which from the character of its antennae appears to belong rather to the Scyllaridae than 

 to the Palinuridfe. The progressive development of the young of the two families is 

 probably so nearly similar, that the history of one would be the repetition of the other. 

 Our specimens, which are numerous, are only 16 mm. in length, or about half that of the 



1 Loc. cit., pi. xxviii. fig. 3, c.d. 



