REPORT ON THE CRUSTACEA MA CRURA. <J01 



unequal flagella, the peduncle of which does not reach to the distal extremity of the 

 ophthalmus. 



The second pair of antennae supports a scaphocerite that is a little longer than the 

 ophthalmopod, rounded at the distal extremity, which is fringed with hairs, and has 

 the outer angle armed with a strong tooth ; the flagellum is one-third shorter than the 

 scaphocerite. 



Amphion, Milne-Edwards. 

 Amphion, Milne-Edwards, Ann. Soc. Entom. France, torn. i. p. 336 ; Hist. Nat. Crust., tom. ii. p. 486. 



In 1832, Professor Milne-Edwards, at a meeting of the Entomological Society of 

 Paris, described a pelagic Crustacean of small size, and extremely pellucid, to which he 

 gave the name of Amphion, and placed it as a new genus along with another that 

 appeared to correspond much with it, to which Leach had given the name of Phyllo- 

 soma, in a famdy to which Milne-Edwards gave the name of Bicuirasses, and placed it 

 among the Stomapoda. 



The genus Phyllosoma has since been demonstrated to be the young and immature 

 form of Crustacea belonging to the families of Palinuridee and Scyllaridae, but' the 

 position of Amphion is still uncertain, its true relation to the adult form not having 

 been hitherto determined. 



Although it possesses some general resemblance to Phyllosoma, it differs most 

 importantly in structural characters, and belongs to a separate division of the order. The 

 general outline of form is very different. In Phyllosoma the carapace is as broad as 

 long and circular in form, and does not cover the pereion, which exists as a second 

 somewhat circular disc posterior to it, whence Milne-Edwards derived the general name 

 for the famdy. 



In Amphion the carapace is long and narrow, and covers the pereion from the 

 earliest to the latest stage of its known development. 



Phyllosoma is known to leave the ovum with five pairs of appendages attached to 

 the pereion, namely, two pairs of gnathopoda and three pairs of pereiopoda ; but although 

 Amphion has never been procured from the ovum, yet there are specimens in this collec- 

 tion in which the only appendages present besides the ophthalmopoda, antennae, and 

 oral organs, are the two pairs of gnathopoda, and they are only distinguishable from 

 the Zoea of the Phyllobranchiate prawns by the presence of the sixth pair of pleopoda in 

 an incipient condition. But even here these pleopods are not present as distinct organs, 

 but are in an early state of gemmation, suggesting a progressive development which shows 

 the animal to have existed for some time in a different condition prior to its previous 

 moult. Our youngest specimen is about 5 mm. in length, and it is highly probable 

 that the brephalos appears in the Zoea stage, whereas in Phyllosoma the pleon is in an 



