484 CRUSTACEA. 



APPENDIX TO THE CRUSTACEA ANOMOURA. 



MEGALOPIDEA. 



THE position of the Megalopae among Crustacea is still a question 

 of much uncertainty. They are placed by Milne Edwards provi- 

 sionally near to Porcellana, in his division " Porcellaniens ;" while 

 De Haan, on account of the structure of the inner and outer maxil- 

 lipeds and expanded abdomen, places them among the Macroura, in 

 a family of his section Astacini. The researches of different authors, 

 moreover, have proved their general resemblance to the young of 

 some Brachyura, suggesting that they may be immature individuals 

 of some known genus or genera; and Milne Edwards remarks on 

 their resemblance to young Dromiae. 



This uncertainty as to their maturity is sustained by the unusual 

 size of their eyes, a character of young Brachyura, and by the non- 

 discovery, as yet, of females with eggs beneath the abdomen. Still, 

 on the other side, we observe, that the species have often a much 

 wider geographical distribution than the Brachyura, to which we 

 might refer them, are known to have. Moreover, there is a number 

 of genera among them, of very different general form, which still 

 have a close similarity, in the position and structure of the inner and 

 outer antennae, and general habit ; showing more diversity amid their 

 resemblances, than we look for among the young of any genus of 

 Brachyura. These considerations are, however, of comparatively 

 small weight, and therefore, instead of placing the Megalopidea in 

 their proper position among the Anomoura, we have left them for an 

 Appendix. 



Their true position, if mature, is probably next to the Anomoura 

 Superiora, in a section that might be designated Anomoura Super- 

 media, being between the Superiora and Media. Like the Anomoura 

 Superiora and the Brachyura, they have the inner and outer antenna) 

 situated between the eyes ; in this point they are far above and much 

 unlike the Porcellanidea, and moreover, the inner antennas fold into 

 fossettes. But, unlike this higher group, the abdomen is elongated, 

 and bears appendages below ; and, although when inflexed, it covers 



